feat(api): роутеры API v1 и WebSocket-поток метрик (Refs #19)

- ops: health/ready/metrics без аутентификации (503 = схема Error).
- auth: login/logout/session, cookie-сессия + CSRF-токен.
- status/config/routing/devices+logs: все эндпоинты контракта.
- ws/metrics: /api/v1/metrics/stream, токен в заголовке или query.

backend/awg_api/ws/metrics.py

@@ -0,0 +1,47 @@
+"""WebSocket-поток метрик: GET /api/v1/metrics/stream."""
+
+from __future__ import annotations
+
+import asyncio
+
+from fastapi import APIRouter, WebSocket, WebSocketDisconnect
+
+from awg_api.deps import SESSION_COOKIE_NAME, token_matches
+from awg_api.state import MockState
+
+router = APIRouter(tags=["metrics"])
+
+WS_ACCESS_DENIED = 4401
+MIN_INTERVAL_MS = 250
+
+
+def _authorized(websocket: WebSocket, token: str | None) -> bool:
+    expected: str = websocket.app.state.api_token
+    header = websocket.headers.get("authorization", "")
+    scheme, _, credentials = header.partition(" ")
+    if scheme.lower() == "bearer" and token_matches(credentials.strip(), expected):
+        return True
+    if token_matches(token, expected):
+        return True
+    session_id = websocket.cookies.get(SESSION_COOKIE_NAME)
+    state: MockState = websocket.app.state.mock_state
+    return token_matches(session_id, state.session_token)
+
+
+@router.websocket("/api/v1/metrics/stream")
+async def stream_metrics(
+    websocket: WebSocket, token: str | None = None, interval_ms: int = 1000
+) -> None:
+    """Отправляет кадры ``WsFrame``: метрики до отключения клиента."""
+    if not _authorized(websocket, token):
+        await websocket.close(code=WS_ACCESS_DENIED)
+        return
+    state: MockState = websocket.app.state.mock_state
+    await websocket.accept()
+    interval_s = max(MIN_INTERVAL_MS, interval_ms) / 1000
+    try:
+        while True:
+            await websocket.send_json(state.metrics_frame())
+            await asyncio.sleep(interval_s)
+    except (WebSocketDisconnect, RuntimeError):
+        return