Рабочий пайплайн: YouTube -> транскрипция -> выжимка -> Postgres

- новый api/: /pipeline/process (yt-dlp, субтитры или Vosk, LLM/экстрактивная
  суммаризация), /videos, /llm; старый код перенесён в api_legacy/
- web/: Flet UI (flet 0.28.3 + flet-web, порт 8550)
- Dockerfile.api: ffmpeg слоем из mwader/static-ffmpeg, pip с кэш-маунтом
- requirements/pyproject: убраны moviepy, imageio-ffmpeg, битый asyncio
- README с инструкцией запуска и загрузкой Vosk-модели

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

api_legacy/db/connection.py

@@ -0,0 +1,27 @@
+from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession
+from sqlalchemy.orm import sessionmaker
+from sqlalchemy import text
+import asyncio
+from api.config import settings
+
+DATABASE_URL = settings.DATABASE_URL
+engine = create_async_engine(DATABASE_URL, echo=False, future=True)
+SessionLocal = sessionmaker(engine, expire_on_commit=False, class_=AsyncSession)
+
+
+async def wait_for_db(retries: int = 30, delay: float = 1.0) -> None:
+	"""Wait until the database is available. Retries with exponential backoff.
+
+	Raises RuntimeError if DB is still unavailable after retries.
+	"""
+	last_exc = None
+	for attempt in range(1, retries + 1):
+		try:
+			async with engine.connect() as conn:
+				await conn.execute(text("SELECT 1"))
+				return
+		except Exception as e:
+			last_exc = e
+			wait = min(delay * (2 ** (attempt - 1)), 5)
+			await asyncio.sleep(wait)
+	raise RuntimeError(f"Could not connect to DB after {retries} attempts") from last_exc