feat(moderation): make moderation more lenient and add timeout fallback behavior

The moderation system now uses a "pass/review" strategy instead of "pass/review/block", treating hard violations the same as review (only routing to manual review rather than auto-rejecting). Add fallback-approve behavior in the hook system so slow moderation APIs never silently block normal content when they time out or get cancelled - timed-out moderation now approves with "ReviewedBy: system" instead of leaving the zero-value result that would reject content. Update post/comment/vote services and handlers to use the new unified behavior. Simplify moderation prompts to emphasize "宁可放过，不可误伤" (prefer false positives over false negatives).

internal/service/comment_service.go

@@ -2,6 +2,7 @@ package service
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"log"
 	"strings"
@@ -170,7 +171,7 @@ func (s *commentService) reviewCommentAsync(
 	fmt.Sscanf(userID, "%d", &authorID)
 
 	result := &hook.ModerationResult{}
-	s.hookManager.TriggerWithMetadata(context.Background(), hook.HookCommentPreModerate, authorID, &hook.CommentModerateHookData{
+	triggerErr := s.hookManager.TriggerWithMetadata(context.Background(), hook.HookCommentPreModerate, authorID, &hook.CommentModerateHookData{
 		CommentID: commentID,
 		PostID:    postID,
 		Content:   content,
@@ -181,6 +182,19 @@ func (s *commentService) reviewCommentAsync(
 		"result": result,
 	})
 
+	// Fallback-approve when a moderation hook times out or is cancelled, so a
+	// slow moderation API never silently rejects an otherwise-fine comment.
+	if triggerErr != nil && (errors.Is(triggerErr, context.DeadlineExceeded) || errors.Is(triggerErr, context.Canceled)) {
+		zap.L().Warn("Comment moderation hook timed out or was cancelled, fallback approve",
+			zap.String("comment_id", commentID),
+			zap.Error(triggerErr),
+		)
+		result.Approved = true
+		result.ReviewedBy = "system"
+		result.RejectReason = ""
+		result.NeedsReview = false
+	}
+
 	s.hookManager.Trigger(context.Background(), hook.HookCommentModerated, authorID, &hook.CommentModeratedHookData{
 		CommentID:    commentID,
 		PostID:       postID,