feat: create backend skeleton

backend/src/api/app.py

@@ -0,0 +1,30 @@
+from collections.abc import AsyncGenerator
+from contextlib import asynccontextmanager
+
+import asyncpg
+from dishka.integrations.fastapi import FromDishka, inject, setup_dishka
+from fastapi import FastAPI
+
+from dependencies.container import container
+
+
+@asynccontextmanager
+async def lifespan(app_: FastAPI) -> AsyncGenerator[None]:
+    yield
+    await app_.state.dishka_container.close()
+
+
+app = FastAPI(title="beavergram API", lifespan=lifespan)
+
+
+@app.get("/health")
+@inject
+async def health(pool: FromDishka[asyncpg.Pool]) -> dict[str, bool]:
+    db_ok = await pool.fetchval("SELECT 1") == 1
+    timescale_ok = await pool.fetchval(
+        "SELECT EXISTS (SELECT 1 FROM pg_extension WHERE extname = 'timescaledb')"
+    )
+    return {"db": db_ok, "timescaledb": bool(timescale_ok)}
+
+
+setup_dishka(container, app)