feat: фаза 3 — i18n RU/EN, /metrics, AI disclaimer, initiator+IP, LLM очередь

3.3 i18n: модуль с RU/EN словарями, LangMiddleware (cookie+query),
     Jinja-фильтр t(), переключатель EN/RU в nav, перевод ключевых
     строк интерфейса
3.5 /metrics: Prometheus-совместимый endpoint (scans_total,
     scans_flagged, findings_total, by_status, by_ecosystem,
     last_scan_timestamp)
3.2 AI disclaimer: сноска под каждым LLM-вердиктом (.llm-disclaimer)
3.4 LLM очередь: asyncio.Semaphore(LLM_MAX_CONCURRENT_ANALYSES)
3.1 initiator + source_ip: поля в Scan, захват из webhook payload,
     показ в scan_detail + API
3.6 UI: убран stat-minibar и heatmap с дашборда

guarddog_nexus/main.py

@@ -4,20 +4,44 @@ import os
 from contextlib import asynccontextmanager
 
 import uvicorn
-from fastapi import FastAPI
+from fastapi import FastAPI, Request
 from fastapi.staticfiles import StaticFiles
+from starlette.middleware.base import BaseHTTPMiddleware
 
 from guarddog_nexus.config import config
 from guarddog_nexus.constants import APP_DESCRIPTION, APP_NAME, APP_PACKAGE, STATIC_MOUNT_PATH
 from guarddog_nexus.db.engine import init_db
+from guarddog_nexus.i18n import DEFAULT_LANG, LANGUAGES
 from guarddog_nexus.logging_setup import log
 from guarddog_nexus.routes import api_findings, api_packages, api_scans
+from guarddog_nexus.routes.metrics import router as metrics_router
 from guarddog_nexus.routes.web import router as web_router
 from guarddog_nexus.routes.webhooks import router as webhook_router
 
 STATIC_DIR = os.path.join(os.path.dirname(__file__), "web", "static")
 
 
+class LangMiddleware(BaseHTTPMiddleware):
+    async def dispatch(self, request: Request, call_next):
+        # Cookie takes priority, then query param, then default
+        cookie_lang = request.cookies.get("lang")
+        query_lang = request.query_params.get("lang")
+
+        if query_lang and query_lang in LANGUAGES and query_lang != cookie_lang:
+            lang = query_lang
+        elif cookie_lang and cookie_lang in LANGUAGES:
+            lang = cookie_lang
+        else:
+            lang = DEFAULT_LANG
+
+        request.state.lang = lang
+        response = await call_next(request)
+
+        if query_lang and query_lang in LANGUAGES:
+            response.set_cookie("lang", query_lang, max_age=365 * 24 * 3600, httponly=True)
+        return response
+
+
 @asynccontextmanager
 async def lifespan(app: FastAPI):
     await init_db()
@@ -32,8 +56,10 @@ app = FastAPI(
     description=APP_DESCRIPTION,
     lifespan=lifespan,
 )
+app.add_middleware(LangMiddleware)
 
 app.include_router(webhook_router)
+app.include_router(metrics_router)
 app.include_router(api_scans.router)
 app.include_router(api_packages.router)
 app.include_router(api_findings.router)