Auth Feature - Fourth Iteration

The third iteration of the auth feature should focus on enhancing the OAuth flow and adding a signout/disconnect feature.

This is a follow up to the initial iterations...

- First Iteration - https://github.com/babblebey/jargons.dev/pull/8
- Second Iteration - https://github.com/babblebey/jargons.dev/pull/28
- OAuth App type refactoring - https://github.com/babblebey/jargons.dev/pull/33

#### Tasks
1. **Store OAuth Flow State Object in Cookies:** Implement the todo that suggests storing the OAuth flow state object to cookies. This stored state should be compared with the `state` param returned from the GitHub OAuth flow in the `github/oauth/callback` handler to prevent CSRF attacks.

#### Related Files
- `github/oauth/callback.js`
- `lib/actions/do-auth.js`

#### Acceptance Criteria
- OAuth flow state object is stored in cookies and compared with the `state` param.
- Signout/disconnect feature is implemented and accessible through the `doAuth` action

#### Additional Notes
- Nothing much... just ask a question or share ideas, if you've got any 😉

Beginne mit dem Lesen von github/oauth/callback.js und lib/actions/do-auth.js und untersuche anschließend den bestehenden OAuth-Flow und dessen TODO für die Cookie-Speicherung. Die Aufgabe ist erledigt, wenn der OAuth-Zustand gespeichert und mit dem zurückgegebenen state-Parameter verglichen wird und signout/disconnect über doAuth verfügbar ist; das Issue nennt keinen auszuführenden Test.

Vom Indexierungsmodell aus dem Issue-Text verfasst.