feat: initial microservices project structure

Services:
- api: FastAPI gateway with JWT auth, async endpoints, WebSocket
- worker-gpu: CUDA sentence-transformers, FAISS IVFFlat, Ollama LLM
- worker-indexer: Winnowing+MinHash plagiarism detection, PDF/DOCX extraction
- worker-notifier: SMTP email notifications
- worker-gost: GOST 7.1-2003 and GOST R 7.0.5-2008 formatting

Infrastructure:
- docker-compose.yml (production) + docker-compose.dev.yml (hot reload)
- Nginx reverse proxy + WebSocket support
- PostgreSQL 16 with Alembic migrations
- Elasticsearch 8 with Russian/English analyzers
- MinIO, RabbitMQ, Redis, Ollama

Frontend:
- React 18 + Vite + TypeScript + TailwindCSS + Zustand + React Query v5
- 9 pages: Home, Search, Cabinet, Task, Check, Bibliography, Pricing, Login, Register

Scripts:
- Parser stubs: OpenAlex, КиберЛенинка, arXiv (Phase 0 - to be filled)

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

services/worker-gost/app/db.py

@@ -0,0 +1,32 @@
+"""Подключение к PostgreSQL для gost-воркера."""
+
+from contextlib import contextmanager
+from typing import Generator
+
+from sqlalchemy import create_engine
+from sqlalchemy.orm import Session, sessionmaker
+
+from app.config import settings
+
+engine = create_engine(
+    settings.database_url_sync,
+    pool_size=5,
+    max_overflow=10,
+    pool_pre_ping=True,
+)
+
+SessionLocal = sessionmaker(bind=engine, autocommit=False, autoflush=False)
+
+
+@contextmanager
+def db_session() -> Generator[Session, None, None]:
+    """Контекстный менеджер для сессии БД."""
+    session = SessionLocal()
+    try:
+        yield session
+        session.commit()
+    except Exception:
+        session.rollback()
+        raise
+    finally:
+        session.close()