feat(backend): add OAuth2/JWT authentication support

- Add OAuth2 client for Authentik integration
- Implement JWT token generation and validation
- Add refresh token support with database storage
- Update database schema with oauth_subject, oauth_provider, and refresh_tokens table
- Create auth package with config, jwt, oauth, and token management
- Add OAuth endpoints: /auth/login, /auth/callback, /auth/refresh, /auth/logout
- Update AuthMiddleware to support both JWT and API key authentication
- Add user helper functions for OAuth user creation and retrieval
- Add .env.example with OAuth configuration template

API keys still work for CLI compatibility while JWT tokens support web/mobile clients.

opal-web/README.md

@@ -0,0 +1,38 @@
+# sv
+
+Everything you need to build a Svelte project, powered by [`sv`](https://github.com/sveltejs/cli).
+
+## Creating a project
+
+If you're seeing this, you've probably already done this step. Congrats!
+
+```sh
+# create a new project in the current directory
+npx sv create
+
+# create a new project in my-app
+npx sv create my-app
+```
+
+## Developing
+
+Once you've created a project and installed dependencies with `npm install` (or `pnpm install` or `yarn`), start a development server:
+
+```sh
+npm run dev
+
+# or start the server and open the app in a new browser tab
+npm run dev -- --open
+```
+
+## Building
+
+To create a production version of your app:
+
+```sh
+npm run build
+```
+
+You can preview the production build with `npm run preview`.
+
+> To deploy your app, you may need to install an [adapter](https://svelte.dev/docs/kit/adapters) for your target environment.