rebuild(stage-1): establish isolated application skeleton

next/backend/http/routes/health.py

@@ -0,0 +1,17 @@
+from fastapi import APIRouter, Request
+from pydantic import BaseModel
+
+router = APIRouter(tags=["health"])
+
+
+class HealthResponse(BaseModel):
+    status: str
+    environment: str
+
+
+@router.get("/health", response_model=HealthResponse)
+def health(request: Request) -> HealthResponse:
+    return HealthResponse(
+        status="ok",
+        environment=request.app.state.settings.environment,
+    )