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.

.env.example

@@ -59,4 +59,11 @@ TURBO_TELEMETRY_DISABLED=1
 # ENABLE_KUBERNETES=true
 
 # Enable mock integration
-UNSAFE_ENABLE_MOCK_INTEGRATION=true
+UNSAFE_ENABLE_MOCK_INTEGRATION=true
+
+# Community marketplace (PocketBase) base URL used by the in-app "Install from marketplace" buttons
+# In production this defaults to https://store.homarr.dev — override for local dev:
+NEXT_PUBLIC_WIDGET_STORE_URL=http://localhost:8090
+# Docs site marketplace URL used for "Open Marketplace" links
+# In production this defaults to https://homarr.dev/marketplace
+# NEXT_PUBLIC_MARKETPLACE_URL=http://localhost:3003/marketplace