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/vote_service.go

@@ -177,7 +177,7 @@ func (s *voteService) reviewVotePostAsync(postID, userID, title, content string,
 	}
 
 	result := &hook.ModerationResult{}
-	s.hookManager.TriggerWithMetadata(context.Background(), hook.HookPostPreModerate, authorID, &hook.PostModerateHookData{
+	triggerErr := s.hookManager.TriggerWithMetadata(context.Background(), hook.HookPostPreModerate, authorID, &hook.PostModerateHookData{
 		PostID:   postID,
 		Title:    title,
 		Content:  content,
@@ -187,6 +187,16 @@ func (s *voteService) reviewVotePostAsync(postID, userID, title, content string,
 		"result": result,
 	})
 
+	// Fallback-approve when a moderation hook times out or is cancelled, so a
+	// slow moderation API never silently rejects an otherwise-fine vote post.
+	if triggerErr != nil && (errors.Is(triggerErr, context.DeadlineExceeded) || errors.Is(triggerErr, context.Canceled)) {
+		log.Printf("[WARN] Vote post moderation hook timed out or was cancelled, fallback approve post=%s err=%v", postID, triggerErr)
+		result.Approved = true
+		result.ReviewedBy = "system"
+		result.RejectReason = ""
+		result.NeedsReview = false
+	}
+
 	s.hookManager.Trigger(context.Background(), hook.HookPostModerated, authorID, &hook.PostModeratedHookData{
 		PostID:       postID,
 		AuthorID:     authorID,