Fix Docker build: lockfile, BuildKit DNS, and setuptools build backend

- Generate frontend/package-lock.json (required by npm ci)
- Add network: host to BuildKit build stages to fix DNS in pip installs
- Switch pyproject.toml build backend to setuptools.build_meta (stable)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/pyproject.toml

@@ -1,6 +1,6 @@
 [build-system]
-requires = ["setuptools"]
+requires = ["setuptools>=45"]
-build-backend = "setuptools.backends.legacy:build"
+build-backend = "setuptools.build_meta"
 
 [project]
 name = "destroying_sap"

changelog/2026-04-12_docker-fixes.md

@@ -0,0 +1,23 @@
+# 2026-04-12 — Fix Docker build issues
+
+**Timestamp:** 2026-04-12T13:40:00
+
+## Summary
+
+Resolved three Docker build failures preventing the dev stack from starting. All three containers (db, backend, frontend) now build and run successfully.
+
+## Issues Fixed
+
+1. **No `package-lock.json`** — `npm ci` requires a lockfile. Generated `frontend/package-lock.json` inside a throwaway `node:20-alpine` container (no host installation).
+2. **BuildKit DNS failure** — Docker BuildKit build steps had no DNS resolution, causing pip to fail on PyPI connections. Fixed by adding `network: host` to both `backend` and `frontend` build configs in `docker-compose.yml`.
+3. **`setuptools.backends.legacy` unavailable** — The `pyproject.toml` referenced a setuptools 68+ only backend path. Changed to the stable `setuptools.build_meta` backend (available since setuptools 40).
+
+## Files Modified
+
+- `docker-compose.yml` — added `network: host` to `backend` and `frontend` build sections
+- `backend/pyproject.toml` — changed build backend from `setuptools.backends.legacy:build` to `setuptools.build_meta`; bumped setuptools requirement to `>=45`
+- `backend/Dockerfile` — reverted intermediate `--no-build-isolation` workaround (no longer needed)
+
+## Files Added
+
+- `frontend/package-lock.json` — npm lockfile required by `npm ci` in the frontend Dockerfile

docker-compose.yml

@@ -23,6 +23,7 @@ services:
     build:
       context: ./backend
       dockerfile: Dockerfile
+      network: host
     restart: unless-stopped
     env_file: ./backend/.env
     environment:
@@ -38,6 +39,7 @@ services:
     build:
       context: ./frontend
       dockerfile: Dockerfile
+      network: host
     restart: unless-stopped
     ports:
       - "80:80"