feat(moderation): add user-facing reasons for rejected or failed content

Prompt AI models to provide short explanations for rejected content
Store reasons in database and broadcast via WebSocket
Display moderation details in UI for authors and admins

backend/db/schema.sql

@@ -197,12 +197,16 @@ CREATE TABLE IF NOT EXISTS ai_moderation_cache (
   model text NOT NULL,
   status text NOT NULL CHECK (status IN ('approved', 'rejected')),
   language_code text REFERENCES languages(code) ON DELETE SET NULL,
+  reason text,
   checked_at timestamptz NOT NULL DEFAULT now(),
   PRIMARY KEY (content_hash, model),
   CHECK (length(content_hash) BETWEEN 32 AND 128),
   CHECK (length(model) BETWEEN 1 AND 120)
 );
 
+ALTER TABLE ai_moderation_cache
+  ADD COLUMN IF NOT EXISTS reason text;
+
 CREATE TABLE IF NOT EXISTS rate_limit_settings (
   id boolean PRIMARY KEY DEFAULT true CHECK (id = true),
   settings jsonb NOT NULL DEFAULT '{}'::jsonb CHECK (jsonb_typeof(settings) = 'object'),
@@ -657,6 +661,7 @@ CREATE TABLE IF NOT EXISTS life_posts (
   game_version_id integer REFERENCES game_versions(id) ON DELETE SET NULL,
   ai_moderation_status text NOT NULL DEFAULT 'unreviewed' CHECK (ai_moderation_status IN ('unreviewed', 'reviewing', 'approved', 'rejected', 'failed')),
   ai_moderation_language_code text REFERENCES languages(code) ON DELETE SET NULL,
+  ai_moderation_reason text,
   ai_moderation_content_hash text,
   ai_moderation_checked_at timestamptz,
   ai_moderation_retry_count integer NOT NULL DEFAULT 0 CHECK (ai_moderation_retry_count >= 0),
@@ -696,6 +701,7 @@ CREATE TABLE IF NOT EXISTS life_post_comments (
   body text NOT NULL CHECK (length(body) BETWEEN 1 AND 1000),
   ai_moderation_status text NOT NULL DEFAULT 'unreviewed' CHECK (ai_moderation_status IN ('unreviewed', 'reviewing', 'approved', 'rejected', 'failed')),
   ai_moderation_language_code text REFERENCES languages(code) ON DELETE SET NULL,
+  ai_moderation_reason text,
   ai_moderation_content_hash text,
   ai_moderation_checked_at timestamptz,
   ai_moderation_retry_count integer NOT NULL DEFAULT 0 CHECK (ai_moderation_retry_count >= 0),
@@ -1186,6 +1192,7 @@ CREATE TABLE IF NOT EXISTS entity_discussion_comments (
   body text NOT NULL CHECK (length(body) BETWEEN 1 AND 1000),
   ai_moderation_status text NOT NULL DEFAULT 'unreviewed' CHECK (ai_moderation_status IN ('unreviewed', 'reviewing', 'approved', 'rejected', 'failed')),
   ai_moderation_language_code text REFERENCES languages(code) ON DELETE SET NULL,
+  ai_moderation_reason text,
   ai_moderation_content_hash text,
   ai_moderation_checked_at timestamptz,
   ai_moderation_retry_count integer NOT NULL DEFAULT 0 CHECK (ai_moderation_retry_count >= 0),
@@ -1238,6 +1245,7 @@ CREATE TABLE IF NOT EXISTS notifications (
   entity_id integer,
   reaction_type text CHECK (reaction_type IS NULL OR reaction_type IN ('like', 'helpful', 'fun', 'thanks')),
   moderation_status text CHECK (moderation_status IS NULL OR moderation_status IN ('approved', 'rejected', 'failed')),
+  moderation_reason text,
   read_at timestamptz,
   created_at timestamptz NOT NULL DEFAULT now(),
   updated_at timestamptz NOT NULL DEFAULT now()
@@ -1278,6 +1286,9 @@ CREATE TABLE IF NOT EXISTS notification_ws_tickets (
 CREATE INDEX IF NOT EXISTS notification_ws_tickets_user_idx
   ON notification_ws_tickets(user_id, expires_at DESC);
 
+ALTER TABLE notifications
+  ADD COLUMN IF NOT EXISTS moderation_reason text;
+
 ALTER TABLE life_tags
   ADD COLUMN IF NOT EXISTS is_rateable boolean NOT NULL DEFAULT false;
 
@@ -1300,6 +1311,7 @@ ALTER TABLE life_posts
   ADD COLUMN IF NOT EXISTS category_id integer REFERENCES life_tags(id) ON DELETE RESTRICT,
   ADD COLUMN IF NOT EXISTS game_version_id integer REFERENCES game_versions(id) ON DELETE SET NULL,
   ADD COLUMN IF NOT EXISTS ai_moderation_language_code text REFERENCES languages(code) ON DELETE SET NULL,
+  ADD COLUMN IF NOT EXISTS ai_moderation_reason text,
   ADD COLUMN IF NOT EXISTS ai_moderation_content_hash text,
   ADD COLUMN IF NOT EXISTS ai_moderation_checked_at timestamptz,
   ADD COLUMN IF NOT EXISTS ai_moderation_retry_count integer NOT NULL DEFAULT 0 CHECK (ai_moderation_retry_count >= 0),
@@ -1342,6 +1354,7 @@ CREATE INDEX IF NOT EXISTS life_post_ratings_user_idx
 ALTER TABLE life_post_comments
   ADD COLUMN IF NOT EXISTS ai_moderation_status text NOT NULL DEFAULT 'unreviewed' CHECK (ai_moderation_status IN ('unreviewed', 'reviewing', 'approved', 'rejected', 'failed')),
   ADD COLUMN IF NOT EXISTS ai_moderation_language_code text REFERENCES languages(code) ON DELETE SET NULL,
+  ADD COLUMN IF NOT EXISTS ai_moderation_reason text,
   ADD COLUMN IF NOT EXISTS ai_moderation_content_hash text,
   ADD COLUMN IF NOT EXISTS ai_moderation_checked_at timestamptz,
   ADD COLUMN IF NOT EXISTS ai_moderation_retry_count integer NOT NULL DEFAULT 0 CHECK (ai_moderation_retry_count >= 0),
@@ -1350,6 +1363,7 @@ ALTER TABLE life_post_comments
 ALTER TABLE entity_discussion_comments
   ADD COLUMN IF NOT EXISTS ai_moderation_status text NOT NULL DEFAULT 'unreviewed' CHECK (ai_moderation_status IN ('unreviewed', 'reviewing', 'approved', 'rejected', 'failed')),
   ADD COLUMN IF NOT EXISTS ai_moderation_language_code text REFERENCES languages(code) ON DELETE SET NULL,
+  ADD COLUMN IF NOT EXISTS ai_moderation_reason text,
   ADD COLUMN IF NOT EXISTS ai_moderation_content_hash text,
   ADD COLUMN IF NOT EXISTS ai_moderation_checked_at timestamptz,
   ADD COLUMN IF NOT EXISTS ai_moderation_retry_count integer NOT NULL DEFAULT 0 CHECK (ai_moderation_retry_count >= 0),