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/post_service.go

@@ -2,6 +2,7 @@ package service
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"log"
 	"strconv"
@@ -216,7 +217,7 @@ func (s *postServiceImpl) reviewPostAsync(postID, userID, title, content string,
 	fmt.Sscanf(userID, "%d", &authorID)
 
 	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,
@@ -226,6 +227,19 @@ func (s *postServiceImpl) reviewPostAsync(postID, userID, title, content string,
 		"result": result,
 	})
 
+	// Trigger can return context.DeadlineExceeded/Canceled if a moderation hook
+	// times out. In that case the result may not have been written at all
+	// (result.Approved stays false). Treat an unfinished moderation as
+	// "approved + system" rather than silently rejecting the post, so a slow
+	// moderation API never blocks normal content.
+	if triggerErr != nil && (errors.Is(triggerErr, context.DeadlineExceeded) || errors.Is(triggerErr, context.Canceled)) {
+		log.Printf("[WARN] 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,