feat: initial FastAPI setup with health endpoint

app/main.py

@@ -0,0 +1,8 @@
+from fastapi import FastAPI
+
+app = FastAPI(title="FFmpeg Worker", version="1.0.0")
+
+
+@app.get("/health")
+async def health() -> dict[str, str]:
+    return {"status": "ok"}

requirements.txt

@@ -0,0 +1,3 @@
+fastapi==0.115.0
+uvicorn[standard]==0.32.0
+pydantic==2.9.0