feat: 按历史痕迹恢复 nginx 同域入口

docs/plans/2026-03-27-production-compose-implementation.md

@@ -103,8 +103,8 @@ Expected: PASS
 
 **Step 3: Check HTTP endpoints**
 
-Run: `curl -i http://127.0.0.1:4173/`
+Run: `curl -i http://127.0.0.1/`
 Expected: `200 OK` and HTML payload
 
-Run: `curl -i http://127.0.0.1:8000/health`
+Run: `curl -i http://127.0.0.1/health`
 Expected: successful backend health response

docs/plans/2026-03-31-restore-nginx-design.md

@@ -0,0 +1,19 @@
+# Restore In-Repo Nginx Design
+
+**Goal:** Restore the repository-managed Nginx entrypoint on `dev` by writing back the earlier removal diff, so frontend static hosting and backend API proxying return to a single same-origin entry.
+
+**Decisions**
+- Restore `nginx/nginx.conf` and `nginx/Dockerfile` from the pre-removal topology.
+- Replace the `frontend` runtime service in `docker-compose.yaml` with an `nginx` service that serves the built SPA and proxies `/api` and `/health` to `backend`.
+- Remove the Caddy-specific runtime file because the repository will no longer use a separate frontend web server.
+- Keep later non-nginx fixes that remain valid, especially the frontend API base URL fallback logic for optional local direct access.
+
+**Architecture**
+- `db` remains unchanged.
+- `backend` remains unchanged and is reachable internally on `backend:8000`.
+- `nginx` becomes the public entrypoint again, serving the frontend bundle and reverse proxying API traffic to `backend`.
+- The browser returns to same-origin access through the Nginx entrypoint.
+
+**Operational Notes**
+- This is an in-place restoration based on the previous removal footprint, not a fresh redesign.
+- The current Tencent Cloud/private registry removal remains intact and is not being reintroduced.