feat(agent): v4.15.0 - panneau Agent style Notion AI (mentions @ inline + skills / + actions sous chaque réponse)

- Composeur contenteditable : mentions inline (pastilles icône+nom), barre de contexte groupée documents/skills, sélecteur @ (icône+titre+chemin), skills intégrés + agent_skills + commandes admin via '/'
- Actions sous chaque réponse agent : copier, insérer dans la page, feedback 👍/👎
- Backend : table agent_feedback, GET /api/agent/mentions, POST /api/agent/feedback, contexte document:<id>/page:<id>/collection:<id> résolu en contenu réel
- Inclut le travail v4.14.0 (documents/espace de travail + outils + auto-titre de conversation)

app/db.py

@@ -723,6 +723,22 @@ def init_db():
                 created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
             )
         """)
+        # ─── v4.15.0: feedback des réponses de l'agent (👍 / 👎) ───────────────
+        conn.execute("""
+            CREATE TABLE IF NOT EXISTS agent_feedback (
+                id INTEGER PRIMARY KEY AUTOINCREMENT,
+                conversation_id INTEGER REFERENCES agent_conversations(id) ON DELETE SET NULL,
+                message_id INTEGER REFERENCES agent_messages(id) ON DELETE SET NULL,
+                user_id INTEGER REFERENCES users(id) ON DELETE SET NULL,
+                rating TEXT NOT NULL CHECK (rating IN ('up', 'down')),
+                snippet TEXT DEFAULT '',
+                comment TEXT DEFAULT '',
+                created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+            )
+        """)
+        conn.execute("CREATE INDEX IF NOT EXISTS idx_agent_feedback_conv ON agent_feedback(conversation_id)")
+        conn.execute("CREATE INDEX IF NOT EXISTS idx_agent_feedback_user ON agent_feedback(user_id)")
+
         conn.execute("CREATE INDEX IF NOT EXISTS idx_agent_conv_user ON agent_conversations(user_id, updated_at)")
         conn.execute("CREATE INDEX IF NOT EXISTS idx_agent_msg_conv ON agent_messages(conversation_id, created_at)")
         conn.execute("CREATE INDEX IF NOT EXISTS idx_agent_action_conv ON agent_actions(conversation_id)")