fix(tauri): restore external links in the folder picker (#225)

## Summary
- restore the GitHub and Discord links on the folder picker in the Tauri
app
- open those links through the desktop opener bridge instead of relying
on browser-only navigation behavior
- include the capability/schema updates needed for the opener path

## Testing
- npm run typecheck --workspace @codenomad/ui
- cargo check --manifest-path packages/tauri-app/src-tauri/Cargo.toml

packages/tauri-app/src-tauri/capabilities/main-window.json

@@ -11,6 +11,7 @@
     "core:menu:default",
     "dialog:allow-open",
     "opener:allow-default-urls",
+    "opener:allow-open-url",
     "notification:allow-is-permission-granted",
     "notification:allow-request-permission",
     "notification:allow-notify",