refactor: replace standard log with zap logger and optimize code patterns

- Migrate all log.Printf/log.Println calls to structured zap logging
- Use cmp.Or for cleaner default value handling
- Replace manual loops with slices.ContainsFunc/IndexFunc
- Add batch query methods (IsLikedBatch, IsFavoritedBatch) to solve N+1 problem
- Update JSON tags from omitempty to omitzero for numeric fields
- Use errgroup-style wg.Go for worker goroutines
- Remove duplicate casbin/v2 dependency (keeping v3)
- Add plans/ to gitignore

internal/service/group_service.go

@@ -1,9 +1,11 @@
 package service
 
 import (
+	"cmp"
 	"errors"
 	"fmt"
-	"log"
+	"maps"
+	"slices"
 	"strconv"
 	"time"
 
@@ -14,6 +16,7 @@ import (
 	"carrot_bbs/internal/pkg/utils"
 	"carrot_bbs/internal/repository"
 
+	"go.uber.org/zap"
 	"gorm.io/gorm"
 )
 
@@ -137,7 +140,10 @@ type groupNoticeMessage struct {
 func (s *groupService) publishGroupNotice(groupID string, notice groupNoticeMessage) {
 	members, _, err := s.groupRepo.GetMembers(groupID, 1, 1000)
 	if err != nil {
-		log.Printf("[groupService] 获取群成员失败: groupID=%s, err=%v", groupID, err)
+		zap.L().Error("获取群成员失败",
+			zap.String("groupID", groupID),
+			zap.Error(err),
+		)
 		return
 	}
 	if s.sseHub != nil {
@@ -368,7 +374,10 @@ func (s *groupService) DissolveGroup(userID string, groupID string) error {
 	// 先删除群组对应的会话（包括参与者、消息）
 	if s.messageRepo != nil {
 		if err := s.messageRepo.DeleteConversationByGroupID(groupID); err != nil {
-			log.Printf("[DissolveGroup] 删除会话失败: groupID=%s, err=%v", groupID, err)
+			zap.L().Warn("删除会话失败",
+				zap.String("groupID", groupID),
+				zap.Error(err),
+			)
 			// 继续删除群组，不因为会话删除失败而中断
 		}
 	}
@@ -453,7 +462,12 @@ func (s *groupService) createSystemNotification(receiverID string, notifyType mo
 		ExtraData:  extra,
 	}
 	if err := s.notifyRepo.Create(notification); err != nil {
-		log.Printf("[groupService] create system notification failed: receiverID=%s type=%s err=%v", receiverID, notifyType, err)
+		zap.L().Warn("create system notification failed",
+			zap.String("component", "groupService"),
+			zap.String("receiverID", receiverID),
+			zap.String("type", string(notifyType)),
+			zap.Error(err),
+		)
 	}
 }
 
@@ -482,13 +496,22 @@ func (s *groupService) broadcastMemberJoinNotice(groupID string, targetUserID st
 				Category: model.CategoryNotification,
 			}
 			if err := s.messageRepo.CreateMessageWithSeq(msg); err != nil {
-				log.Printf("[broadcastMemberJoinNotice] 保存入群提示消息失败: groupID=%s, userID=%s, err=%v", groupID, targetUserID, err)
+				zap.L().Warn("保存入群提示消息失败",
+					zap.String("component", "broadcastMemberJoinNotice"),
+					zap.String("groupID", groupID),
+					zap.String("userID", targetUserID),
+					zap.Error(err),
+				)
 			} else {
 				savedMessage = msg
 				s.invalidateConversationCachesAfterSystemMessage(conv.ID)
 			}
 		} else {
-			log.Printf("[broadcastMemberJoinNotice] 获取群组会话失败: groupID=%s, err=%v", groupID, err)
+			zap.L().Warn("获取群组会话失败",
+				zap.String("component", "broadcastMemberJoinNotice"),
+				zap.String("groupID", groupID),
+				zap.Error(err),
+			)
 		}
 	}
 
@@ -542,7 +565,12 @@ func (s *groupService) addMemberToGroupAndConversation(group *model.Group, userI
 		conv, err := s.messageRepo.GetConversationByGroupID(group.ID)
 		if err == nil && conv != nil {
 			if err := s.messageRepo.AddParticipant(conv.ID, userID); err != nil {
-				log.Printf("[addMemberToGroupAndConversation] 添加会话参与者失败: groupID=%s, userID=%s, err=%v", group.ID, userID, err)
+				zap.L().Warn("添加会话参与者失败",
+					zap.String("component", "addMemberToGroupAndConversation"),
+					zap.String("groupID", group.ID),
+					zap.String("userID", userID),
+					zap.Error(err),
+				)
 			}
 			s.invalidateConversationCachesAfterMembershipChange(conv.ID, userID)
 		}
@@ -568,11 +596,7 @@ func (s *groupService) collectGroupReviewerIDs(groupID string, ownerID string, s
 		}
 	}
 
-	result := make([]string, 0, len(reviewerSet))
-	for id := range reviewerSet {
-		result = append(result, id)
-	}
-	return result
+	return slices.Collect(maps.Keys(reviewerSet))
 }
 
 func (s *groupService) notifyJoinApplyReviewers(
@@ -655,10 +679,8 @@ func (s *groupService) InviteMembers(userID string, groupID string, memberIDs []
 	inviter, _ := s.userRepo.GetByID(userID)
 	inviterName := "群成员"
 	inviterAvatar := ""
-	if inviter != nil && inviter.Nickname != "" {
-		inviterName = inviter.Nickname
-	}
 	if inviter != nil {
+		inviterName = cmp.Or(inviter.Nickname, "群成员")
 		inviterAvatar = inviter.Avatar
 	}
 
@@ -743,10 +765,8 @@ func (s *groupService) JoinGroup(userID string, groupID string) error {
 			applicant, _ := s.userRepo.GetByID(userID)
 			applicantName := "用户"
 			applicantAvatar := ""
-			if applicant != nil && applicant.Nickname != "" {
-				applicantName = applicant.Nickname
-			}
 			if applicant != nil {
+				applicantName = cmp.Or(applicant.Nickname, "用户")
 				applicantAvatar = applicant.Avatar
 			}
 			// 已有待审批单时补发一次提醒，避免管理端漏看
@@ -767,10 +787,8 @@ func (s *groupService) JoinGroup(userID string, groupID string) error {
 		applicant, _ := s.userRepo.GetByID(userID)
 		applicantName := "用户"
 		applicantAvatar := ""
-		if applicant != nil && applicant.Nickname != "" {
-			applicantName = applicant.Nickname
-		}
 		if applicant != nil {
+			applicantName = cmp.Or(applicant.Nickname, "用户")
 			applicantAvatar = applicant.Avatar
 		}
 		expireAt := time.Now().Add(72 * time.Hour)
@@ -856,9 +874,7 @@ func (s *groupService) RespondInvite(userID string, flag string, approve bool, r
 			targetUserName := "用户"
 			targetUserAvatar := ""
 			if u, e := s.userRepo.GetByID(userID); e == nil && u != nil {
-				if u.Nickname != "" {
-					targetUserName = u.Nickname
-				}
+				targetUserName = cmp.Or(u.Nickname, "用户")
 				targetUserAvatar = u.Avatar
 			}
 
@@ -866,9 +882,7 @@ func (s *groupService) RespondInvite(userID string, flag string, approve bool, r
 			inviterName := "群成员"
 			inviterAvatar := ""
 			if u, e := s.userRepo.GetByID(req.InitiatorID); e == nil && u != nil {
-				if u.Nickname != "" {
-					inviterName = u.Nickname
-				}
+				inviterName = cmp.Or(u.Nickname, "群成员")
 				inviterAvatar = u.Avatar
 			}
 
@@ -962,15 +976,13 @@ func (s *groupService) SetGroupAddRequest(userID string, flag string, approve bo
 	// 保存管理员ID到ReviewerID（覆盖被邀请人的ID）
 	req.Reason = reason
 	targetUserName := "用户"
-	if u, e := s.userRepo.GetByID(req.TargetUserID); e == nil && u != nil && u.Nickname != "" {
-		targetUserName = u.Nickname
+	if u, e := s.userRepo.GetByID(req.TargetUserID); e == nil && u != nil {
+		targetUserName = cmp.Or(u.Nickname, "用户")
 	}
 	reviewerName := "管理员"
 	reviewerAvatar := ""
 	if u, e := s.userRepo.GetByID(userID); e == nil && u != nil {
-		if u.Nickname != "" {
-			reviewerName = u.Nickname
-		}
+		reviewerName = cmp.Or(u.Nickname, "管理员")
 		reviewerAvatar = u.Avatar
 	}
 
@@ -1185,7 +1197,12 @@ func (s *groupService) RemoveMember(userID string, groupID string, targetUserID
 		conv, err := s.messageRepo.GetConversationByGroupID(groupID)
 		if err == nil && conv != nil {
 			if err := s.messageRepo.RemoveParticipant(conv.ID, targetUserID); err != nil {
-				log.Printf("[RemoveMember] 移除会话参与者失败: groupID=%s, userID=%s, err=%v", groupID, targetUserID, err)
+				zap.L().Warn("移除会话参与者失败",
+					zap.String("component", "RemoveMember"),
+					zap.String("groupID", groupID),
+					zap.String("userID", targetUserID),
+					zap.Error(err),
+				)
 			}
 			s.invalidateConversationCachesAfterMembershipChange(conv.ID, targetUserID)
 		}
@@ -1330,22 +1347,35 @@ func (s *groupService) MuteMember(userID string, groupID string, targetUserID st
 
 	member, err := s.groupRepo.GetMember(groupID, targetUserID)
 	if err != nil {
-		log.Printf("[MuteMember] 获取成员失败: %v", err)
+		zap.L().Warn("获取成员失败",
+			zap.String("component", "MuteMember"),
+			zap.Error(err),
+		)
 		return err
 	}
 
-	log.Printf("[MuteMember] 禁言前状态: member.Muted=%v, 即将设置 muted=%v", member.Muted, muted)
+	zap.L().Debug("禁言前状态",
+		zap.String("component", "MuteMember"),
+		zap.Bool("member.Muted", member.Muted),
+		zap.Bool("muted", muted),
+	)
 	member.Muted = muted
 	if err := s.groupRepo.UpdateMember(member); err != nil {
-		log.Printf("[MuteMember] 更新成员失败: %v", err)
+		zap.L().Warn("更新成员失败",
+			zap.String("component", "MuteMember"),
+			zap.Error(err),
+		)
 		return err
 	}
-	log.Printf("[MuteMember] 禁言状态已更新到数据库")
+	zap.L().Debug("禁言状态已更新到数据库", zap.String("component", "MuteMember"))
 
 	// 验证更新结果
 	updatedMember, _ := s.groupRepo.GetMember(groupID, targetUserID)
 	if updatedMember != nil {
-		log.Printf("[MuteMember] 验证: member.Muted=%v", updatedMember.Muted)
+		zap.L().Debug("验证成员状态",
+			zap.String("component", "MuteMember"),
+			zap.Bool("member.Muted", updatedMember.Muted),
+		)
 	}
 
 	// 获取被禁言用户的显示名称
@@ -1382,14 +1412,24 @@ func (s *groupService) MuteMember(userID string, groupID string, targetUserID st
 
 			// 保存消息并获取 seq
 			if err := s.messageRepo.CreateMessageWithSeq(msg); err != nil {
-				log.Printf("[MuteMember] 保存禁言消息失败: %v", err)
+				zap.L().Warn("保存禁言消息失败",
+					zap.String("component", "MuteMember"),
+					zap.Error(err),
+				)
 			} else {
 				savedMessage = msg
-				log.Printf("[MuteMember] 禁言消息已保存, ID=%s, Seq=%d", msg.ID, msg.Seq)
+				zap.L().Debug("禁言消息已保存",
+					zap.String("component", "MuteMember"),
+					zap.String("msgID", msg.ID),
+					zap.Int64("seq", msg.Seq),
+				)
 				s.invalidateConversationCachesAfterSystemMessage(conv.ID)
 			}
 		} else {
-			log.Printf("[MuteMember] 获取群组会话失败: %v", err)
+			zap.L().Warn("获取群组会话失败",
+				zap.String("component", "MuteMember"),
+				zap.Error(err),
+			)
 		}
 	}