fix: аудит — 19 фиксов безопасности, надёжности, UI и 16 новых тестов

- S4: bump jinja2>=3.1.4, python-multipart>=0.0.18, httpx>=0.28.0
- S5: _detect_ecosystem — DEFAULT_ECOSYSTEM для неизвестных форматов
- S6: harvester — log.exception() вместо log.error()
- S8: _scan_component — urlencode параметров
- P1: scanner — proc.kill() при таймауте
- P3: api_packages — selectinload(Scan.findings), убран N+1
- P4+P5: утечка _url_locks и _llm_locks при early return
- P6: DB reaper — сброс {'status':'analyzing'} при старте
- UI: htmx-пагинация, фильтры не теряют flagged, 404 с layout
- UI: мобильные таблицы overflow-x, полная стата на дашборде
- UI: i18n статусов в _status_badge, urlencode package_name
- 16 новых тестов: analyze endpoint (6), scanner errors (4),
  webhook signature (2), llm client (4)

guarddog_nexus/db/engine.py

@@ -1,6 +1,5 @@
 """Async SQLite database setup via SQLAlchemy."""
 
-
 from sqlalchemy import inspect, text
 from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
 from sqlalchemy.orm import DeclarativeBase
@@ -69,6 +68,7 @@ async def init_db():
         await conn.run_sync(Base.metadata.create_all)
     await _migrate()
     await _ensure_indexes()
+    await _reap_stale_analysis()
 
 
 async def get_session() -> AsyncSession:
@@ -90,3 +90,17 @@ async def _ensure_indexes():
     async with _engine.begin() as conn:
         for sql in indexes:
             await conn.execute(text(sql))
+
+
+async def _reap_stale_analysis():
+    """Reset stuck 'analyzing' statuses left from crashes."""
+    sql = (
+        "UPDATE findings SET report = NULL "
+        "WHERE report IS NOT NULL "
+        "AND json_extract(report, '$.status') = 'analyzing'"
+    )
+    async with _engine.begin() as conn:
+        result = await conn.execute(text(sql))
+        count = result.rowcount
+        if count:
+            log.warning("Reset %d stale LLM analysis statuses", count)