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.

example-oauth2-server/website/app.py

@@ -0,0 +1,36 @@
+import os
+from flask import Flask
+from .models import db
+from .oauth2 import config_oauth
+from .routes import bp
+
+
+def create_app(config=None):
+    app = Flask(__name__)
+
+    # load default configuration
+    app.config.from_object('website.settings')
+
+    # load environment configuration
+    if 'WEBSITE_CONF' in os.environ:
+        app.config.from_envvar('WEBSITE_CONF')
+
+    # load app specified configuration
+    if config is not None:
+        if isinstance(config, dict):
+            app.config.update(config)
+        elif config.endswith('.py'):
+            app.config.from_pyfile(config)
+
+    setup_app(app)
+    return app
+
+
+def setup_app(app):
+
+    db.init_app(app)
+    # Create tables if they do not exist already
+    with app.app_context():
+        db.create_all()
+    config_oauth(app)
+    app.register_blueprint(bp, url_prefix='')