feat: /notify command for runtime notification filter control (#161)

Add /notify Telegram command for adjusting notification filters at runtime
without restarting the service:

  /notify                  → show current filter state
  /notify scenario off     → disable scenario match alerts
  /notify market off       → disable market open/close alerts
  /notify all off          → disable all (circuit_breaker always on)
  /notify trades on        → re-enable trade execution alerts

Changes:
- NotificationFilter: add KEYS class var, set_flag(), as_dict()
- TelegramClient: add set_notification(), filter_status()
- TelegramCommandHandler: add register_command_with_args() + args dispatch
- main.py: handle_notify() handler + register /notify command + /help update
- Tests: 12 new tests (set_flag, set_notification, register_command_with_args)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/notifications/telegram_client.py

@@ -4,8 +4,9 @@ import asyncio
 import logging
 import time
 from collections.abc import Awaitable, Callable
-from dataclasses import dataclass
+from dataclasses import dataclass, fields
 from enum import Enum
+from typing import ClassVar
 
 import aiohttp
 
@@ -65,6 +66,17 @@ class NotificationFilter:
     circuit_breaker is intentionally omitted — it is always sent regardless.
     """
 
+    # Maps user-facing command keys to dataclass field names
+    KEYS: ClassVar[dict[str, str]] = {
+        "trades": "trades",
+        "market": "market_open_close",
+        "fatfinger": "fat_finger",
+        "system": "system_events",
+        "playbook": "playbook",
+        "scenario": "scenario_match",
+        "errors": "errors",
+    }
+
     trades: bool = True
     market_open_close: bool = True
     fat_finger: bool = True
@@ -73,6 +85,18 @@ class NotificationFilter:
     scenario_match: bool = True
     errors: bool = True
 
+    def set_flag(self, key: str, value: bool) -> bool:
+        """Set a filter flag by user-facing key. Returns False if key is unknown."""
+        field = self.KEYS.get(key.lower())
+        if field is None:
+            return False
+        setattr(self, field, value)
+        return True
+
+    def as_dict(self) -> dict[str, bool]:
+        """Return {user_key: current_value} for display."""
+        return {k: getattr(self, field) for k, field in self.KEYS.items()}
+
 
 @dataclass
 class NotificationMessage:
@@ -137,6 +161,26 @@ class TelegramClient:
         if self._session is not None and not self._session.closed:
             await self._session.close()
 
+    def set_notification(self, key: str, value: bool) -> bool:
+        """Toggle a notification type by user-facing key at runtime.
+
+        Args:
+            key: User-facing key (e.g. "scenario", "market", "all")
+            value: True to enable, False to disable
+
+        Returns:
+            True if key was valid, False if unknown.
+        """
+        if key == "all":
+            for k in NotificationFilter.KEYS:
+                self._filter.set_flag(k, value)
+            return True
+        return self._filter.set_flag(key, value)
+
+    def filter_status(self) -> dict[str, bool]:
+        """Return current per-type filter state keyed by user-facing names."""
+        return self._filter.as_dict()
+
     async def send_message(self, text: str, parse_mode: str = "HTML") -> bool:
         """
         Send a generic text message to Telegram.
@@ -468,6 +512,7 @@ class TelegramCommandHandler:
         self._client = client
         self._polling_interval = polling_interval
         self._commands: dict[str, Callable[[], Awaitable[None]]] = {}
+        self._commands_with_args: dict[str, Callable[[list[str]], Awaitable[None]]] = {}
         self._last_update_id = 0
         self._polling_task: asyncio.Task[None] | None = None
         self._running = False
@@ -476,7 +521,7 @@ class TelegramCommandHandler:
         self, command: str, handler: Callable[[], Awaitable[None]]
     ) -> None:
         """
-        Register a command handler.
+        Register a command handler (no arguments).
 
         Args:
             command: Command name (without leading slash, e.g., "start")
@@ -485,6 +530,19 @@ class TelegramCommandHandler:
         self._commands[command] = handler
         logger.debug("Registered command handler: /%s", command)
 
+    def register_command_with_args(
+        self, command: str, handler: Callable[[list[str]], Awaitable[None]]
+    ) -> None:
+        """
+        Register a command handler that receives trailing arguments.
+
+        Args:
+            command: Command name (without leading slash, e.g., "notify")
+            handler: Async function receiving list of argument tokens
+        """
+        self._commands_with_args[command] = handler
+        logger.debug("Registered command handler (with args): /%s", command)
+
     async def start_polling(self) -> None:
         """Start long polling for commands."""
         if self._running:
@@ -605,11 +663,14 @@ class TelegramCommandHandler:
             # Remove @botname suffix if present (for group chats)
             command_name = command_parts[0].split("@")[0]
 
-            # Execute handler
-            handler = self._commands.get(command_name)
-            if handler:
+            # Execute handler (args-aware handlers take priority)
+            args_handler = self._commands_with_args.get(command_name)
+            if args_handler:
+                logger.info("Executing command: /%s %s", command_name, command_parts[1:])
+                await args_handler(command_parts[1:])
+            elif command_name in self._commands:
                 logger.info("Executing command: /%s", command_name)
-                await handler()
+                await self._commands[command_name]()
             else:
                 logger.debug("Unknown command: /%s", command_name)
                 await self._client.send_message(