feat: Add OAuth2 server and client implementation with PKCE support

- Implemented OAuth2 server with client registration, authorization, and token endpoints.
- Created HTML templates for client authorization, client creation, and client editing.
- Developed an OAuth2 client application using Hono.js and Bun, supporting authorization code grant flow.
- Integrated PKCE (Proof Key for Code Exchange) for enhanced security during authorization.
- Added session management using cookies for user authentication.
- Included detailed README documentation for setup and usage instructions.

oauth2-attacker/README.md

@@ -0,0 +1,15 @@
+# oauth2-attacker
+
+To install dependencies:
+
+```bash
+bun install
+```
+
+To run:
+
+```bash
+bun run index.ts
+```
+
+This project was created using `bun init` in bun v1.2.18. [Bun](https://bun.sh) is a fast all-in-one JavaScript runtime.