fix: support AI commands in media captions

tests/test_dispatcher.py

@@ -8,6 +8,32 @@ from app.commands import CommandDispatcher, CommandRegistry
 
 
 class CommandDispatcherTests(unittest.IsolatedAsyncioTestCase):
+    async def test_command_in_media_caption_is_dispatched(self) -> None:
+        registry = CommandRegistry()
+        handler = AsyncMock()
+        registry.command("photo", "Caption command")(handler)
+        dispatcher = CommandDispatcher(registry)
+        message = SimpleNamespace(
+            text=None,
+            caption=".photo argument",
+            from_user=SimpleNamespace(id=123),
+            reply_text=AsyncMock(),
+        )
+        account = SimpleNamespace(me=SimpleNamespace(id=123), acl_store=None)
+
+        handled = await dispatcher.dispatch(
+            client=SimpleNamespace(),
+            message=message,
+            manager=SimpleNamespace(),
+            account=account,
+        )
+
+        self.assertTrue(handled)
+        handler.assert_awaited_once()
+        context = handler.await_args.args[0]
+        self.assertEqual(context.args, "argument")
+        self.assertEqual(context.raw_text, ".photo argument")
+
     async def test_unknown_owner_command_is_silent(self) -> None:
         dispatcher = CommandDispatcher(CommandRegistry())
         message = SimpleNamespace(