feat: local tier gateway with PGlite + Gitea-only publishing + repo linking

- Add PGlite (embedded Postgres) for local tier — gateway runs without
  external PG server. Same schema, same Drizzle API, zero module refactor.
- Install wizard now offers tier selection (local vs team).
  Local skips DATABASE_URL/VALKEY_URL, writes mosaic.config.json.
- Comment out npmjs publish step in CI (preserved for future use).
- Revert gateway publishConfig to Gitea registry, include in Gitea publish.
- Add repository field to all 23 publishable package.json files for
  Gitea package-to-repo linking.

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

packages/db/package.json

@@ -1,6 +1,11 @@
 {
   "name": "@mosaic/db",
   "version": "0.0.2",
+  "repository": {
+    "type": "git",
+    "url": "https://git.mosaicstack.dev/mosaic/mosaic-stack.git",
+    "directory": "packages/db"
+  },
   "type": "module",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
@@ -28,6 +33,7 @@
     "vitest": "^2.0.0"
   },
   "dependencies": {
+    "@electric-sql/pglite": "^0.2.17",
     "drizzle-orm": "^0.45.1",
     "postgres": "^3.4.8"
   },