refactor: upgrade to Go 1.26 and modernize code idioms

- Replace `interface{}` with `any` type alias across all packages
- Use built-in `min()`/`max()` for parameter clamping
- Use `slices.SortFunc`, `slices.Min`, `slices.Max` for cleaner code
- Use `strings.Cut()` for simpler string parsing in auth middleware
- Use `errors.Is()` for proper error comparison in handlers
- Update dependencies: golang.org/x/image 0.37.0 -> 0.38.0
- Add Wire code generation guidelines to ARCHITECTURE.md
- Disable Go cache in CI build workflow

internal/repository/message_repo.go

@@ -91,7 +91,7 @@ func (r *messageRepository) CreateConversationWithParticipants(conv *model.Conve
 			participant := model.ConversationParticipant{
 				ConversationID: conv.ID,
 				UserID:         userID,
-				LastReadSeq:     0,
+				LastReadSeq:    0,
 			}
 			if err := tx.Create(&participant).Error; err != nil {
 				return err
@@ -291,7 +291,7 @@ func (r *messageRepository) UpdateLastReadSeq(conversationID string, userID stri
 				{Name: "conversation_id"},
 				{Name: "user_id"},
 			},
-			DoUpdates: clause.Assignments(map[string]interface{}{
+			DoUpdates: clause.Assignments(map[string]any{
 				"last_read_seq": lastReadSeq,
 				"updated_at":    gorm.Expr("CURRENT_TIMESTAMP"),
 			}),
@@ -324,7 +324,7 @@ func (r *messageRepository) UpdatePinned(conversationID string, userID string, i
 				{Name: "conversation_id"},
 				{Name: "user_id"},
 			},
-			DoUpdates: clause.Assignments(map[string]interface{}{
+			DoUpdates: clause.Assignments(map[string]any{
 				"is_pinned":  isPinned,
 				"updated_at": gorm.Expr("CURRENT_TIMESTAMP"),
 			}),
@@ -358,7 +358,7 @@ func (r *messageRepository) GetUnreadCount(conversationID string, userID string)
 func (r *messageRepository) UpdateConversationLastSeq(conversationID string, seq int64) error {
 	return r.db.Model(&model.Conversation{}).
 		Where("id = ?", conversationID).
-		Updates(map[string]interface{}{
+		Updates(map[string]any{
 			"last_seq":      seq,
 			"last_msg_time": gorm.Expr("CURRENT_TIMESTAMP"),
 		}).Error
@@ -393,7 +393,7 @@ func (r *messageRepository) CreateMessageWithSeq(msg *model.Message) error {
 		// 更新会话的last_seq
 		if err := tx.Model(&model.Conversation{}).
 			Where("id = ?", msg.ConversationID).
-			Updates(map[string]interface{}{
+			Updates(map[string]any{
 				"last_seq":      msg.Seq,
 				"last_msg_time": gorm.Expr("CURRENT_TIMESTAMP"),
 			}).Error; err != nil {
@@ -455,7 +455,7 @@ func (r *messageRepository) UpdateMessageStatus(messageID string, status model.M
 func (r *messageRepository) RecallMessage(messageID string, userID string) error {
 	return r.db.Model(&model.Message{}).
 		Where("id = ? AND sender_id = ?", messageID, userID).
-		Updates(map[string]interface{}{
+		Updates(map[string]any{
 			"status":   model.MessageStatusRecalled,
 			"segments": model.MessageSegments{},
 		}).Error
@@ -526,7 +526,7 @@ func (r *messageRepository) MarkAllSystemMessagesAsRead(userID string) error {
 			{Name: "conversation_id"},
 			{Name: "user_id"},
 		},
-		DoUpdates: clause.Assignments(map[string]interface{}{
+		DoUpdates: clause.Assignments(map[string]any{
 			"last_read_seq": maxSeq,
 			"updated_at":    gorm.Expr("CURRENT_TIMESTAMP"),
 		}),
@@ -653,7 +653,7 @@ func (r *messageRepository) BatchUpdateParticipants(ctx context.Context, updates
 
 	var cases []string
 	var whereClauses []string
-	var args []interface{}
+	var args []any
 
 	for _, u := range updates {
 		cases = append(cases, "WHEN (conversation_id = ? AND user_id = ?) THEN ?")
@@ -678,7 +678,7 @@ func (r *messageRepository) UpdateConversationLastSeqWithContext(ctx context.Con
 	return r.db.WithContext(ctx).
 		Model(&model.Conversation{}).
 		Where("id = ?", convID).
-		Updates(map[string]interface{}{
+		Updates(map[string]any{
 			"last_seq":      lastSeq,
 			"last_msg_time": lastMsgTime,
 			"updated_at":    time.Now(),
@@ -701,7 +701,7 @@ func (r *messageRepository) BatchUpdateParticipantsWithTx(tx *gorm.DB, updates [
 
 	var cases []string
 	var whereClauses []string
-	var args []interface{}
+	var args []any
 
 	for _, u := range updates {
 		cases = append(cases, "WHEN (conversation_id = ? AND user_id = ?) THEN ?")
@@ -725,7 +725,7 @@ func (r *messageRepository) BatchUpdateParticipantsWithTx(tx *gorm.DB, updates [
 func (r *messageRepository) UpdateConversationLastSeqWithTx(tx *gorm.DB, convID string, lastSeq int64, lastMsgTime time.Time) error {
 	return tx.Model(&model.Conversation{}).
 		Where("id = ?", convID).
-		Updates(map[string]interface{}{
+		Updates(map[string]any{
 			"last_seq":      lastSeq,
 			"last_msg_time": lastMsgTime,
 			"updated_at":    time.Now(),