chore: overhaul infrastructure and integrate @mintel packages

- Restructure to pnpm monorepo (site moved to apps/web)
- Integrate @mintel/tsconfig, @mintel/eslint-config, @mintel/husky-config
- Implement Docker service architecture (Varnish, Directus, Gatekeeper)
- Setup environment-aware Gitea Actions deployment

pnpm-workspace.yaml

@@ -0,0 +1,3 @@
+packages:
+  - 'apps/*'
+  - 'packages/*'