feat(server): add /status command handler for webhook providers

The generic-webhook provider has no upstream API, so /status reports
DB-derived stats: active/total trackers, provider name, and last event
timestamp (formatted via the shared get_last_event_str helper).

Includes pytest coverage for handler registration, populated stats with
a recent event, the empty-state dash sentinel, and unknown-command
fall-through. Template variable docs in command_template_configs.py
extended with the new trackers_active/trackers_total keys.

packages/server/src/notify_bridge_server/commands/webhook_handler.py

@@ -0,0 +1,89 @@
+"""Generic webhook provider bot command handler.
+
+The generic webhook provider has no upstream API to query — its only
+runtime signal is the stream of incoming webhook payloads recorded as
+``EventLog`` rows.  ``/status`` therefore reports DB-derived stats:
+
+* ``trackers_active`` — enabled ``NotificationTracker`` rows for the provider
+* ``trackers_total`` — all ``NotificationTracker`` rows for the provider
+* ``provider_name`` — the provider's display name
+* ``last_event`` — formatted timestamp of the most recent received event,
+  or ``-`` if nothing has been received yet
+"""
+
+from __future__ import annotations
+
+from typing import Any
+
+from sqlmodel import select
+from sqlmodel.ext.asyncio.session import AsyncSession
+
+from ..database.engine import get_engine
+from ..database.models import (
+    CommandConfig,
+    CommandTracker,
+    CommandTrackerListener,
+    NotificationTracker,
+    ServiceProvider,
+    TelegramBot,
+)
+from .base import CommandResponse, ProviderCommandHandler
+from .command_utils import get_last_event_str
+from .handler import _render_cmd_template
+
+_WEBHOOK_COMMANDS = {"status"}
+
+
+async def _cmd_status(provider: ServiceProvider) -> dict[str, Any]:
+    """Build the context for ``/status`` on a webhook provider."""
+    engine = get_engine()
+    async with AsyncSession(engine) as session:
+        result = await session.exec(
+            select(NotificationTracker).where(
+                NotificationTracker.provider_id == provider.id
+            )
+        )
+        trackers = list(result.all())
+
+    active = [t for t in trackers if t.enabled]
+    last_str = await get_last_event_str([t.id for t in active])
+
+    return {
+        "trackers_active": len(active),
+        "trackers_total": len(trackers),
+        "provider_name": provider.name or "",
+        "last_event": last_str,
+    }
+
+
+class WebhookCommandHandler(ProviderCommandHandler):
+    """Handles ``/status`` for generic-webhook providers."""
+
+    provider_type = "webhook"
+
+    def get_provider_commands(self) -> set[str]:
+        return _WEBHOOK_COMMANDS
+
+    async def handle(
+        self,
+        cmd: str,
+        args: str,
+        count: int,
+        locale: str,
+        response_mode: str,
+        provider: ServiceProvider,
+        cmd_templates: dict[str, dict[str, str]],
+        bot: TelegramBot,
+        tracker: CommandTracker,
+        config: CommandConfig,
+        *,
+        listener: CommandTrackerListener | None = None,
+        allowed_album_ids: set[str] | None = None,  # noqa: ARG002 — webhook has no album scope
+        page: int = 1,
+    ) -> CommandResponse | None:
+        if cmd != "status":
+            return None
+        ctx = await _cmd_status(provider)
+        return CommandResponse(
+            text=_render_cmd_template(cmd_templates, "status", locale, ctx),
+        )