feat: add community marketplace for custom widgets and CSS

Adds a PocketBase-backed marketplace where users can share custom widgets
and CSS themes. Includes a Docusaurus storefront with GitHub OAuth login,
submission/voting/comments, and a PocketBase SQL view that computes author
names, vote counts, and comment counts without fragile hooks. The Next.js
app gets a modal browser for one-click install from the marketplace plus
clipboard paste-to-import on the custom widgets pages.

package.json

@@ -17,6 +17,7 @@
     "db:studio": "pnpm -F db studio",
     "dev": "pnpm -F nextjs dev",
     "dev:docs": "pnpm -F @homarr/docs dev",
+    "dev:marketplace": "docker compose -f ./apps/store/docker-compose.yml up",
     "docker:dev": "docker compose -f ./development/development.docker-compose.yml up",
     "format": "turbo format --continue -- --check",
     "format:fix": "turbo format --continue",