refactor: remove GitHub webhook support

app/manager.py

@@ -9,7 +9,6 @@ from pyrogram import Client, idle
 from app.agentic import AgentSessionStore
 from app.commands import DEFAULT_REGISTRY, CommandRegistry, RuntimeAclStore
 from app.config import AccountConfig, AppConfig
-from app.github_webhook import GitHubWebhookServer
 from app.handlers import register_common_handlers
 
 log = logging.getLogger(__name__)
@@ -31,12 +30,10 @@ class AccountManager:
     config: AppConfig
     command_registry: CommandRegistry = field(init=False)
     states: list[AccountState] = field(init=False)
-    github_webhook_server: GitHubWebhookServer = field(init=False)
 
     def __post_init__(self) -> None:
         self.command_registry = DEFAULT_REGISTRY
         self.states = [AccountState(config=account) for account in self.config.accounts]
-        self.github_webhook_server = GitHubWebhookServer(self, self.config.github_webhook)
 
     def _make_client(self, account: AccountConfig) -> Client:
         api_id = account.api_id if account.api_id is not None else self.config.api_id
@@ -146,8 +143,6 @@ class AccountManager:
             raise RuntimeError("No accounts were started successfully")
 
         try:
-            await self.github_webhook_server.start()
             await idle()
         finally:
-            await self.github_webhook_server.stop()
             await self.stop_all()