Unify auth and MCP servers into single modular codebase

- Merge auth-server and mcp-server into unified architecture under src/modules/
- Add configurable auth modes: internal (single process) and external (separate processes)
- Update example scripts to support OAuth discovery and both auth modes
- Consolidate OAuth documentation into comprehensive implementation guide
- Add configuration options for development vs production deployments
- Support both Redis-backed and in-memory session storage

.env.example

@@ -0,0 +1,38 @@
+# Server Configuration
+PORT=3232
+BASE_URI=http://localhost:3232
+
+# Auth Mode Configuration
+# Options: 'internal' or 'external'
+#
+# - internal: Run auth server in-process (suitable for demo/development)
+#   `npm run dev:internal` starts the server in this mode.
+#   This mode is the default when AUTH_MODE is not set.
+#
+# - external: Use external auth server (production pattern)
+#   `npm run dev:external` starts the server in this mode,
+#   and also starts the demo auth server
+#
+AUTH_MODE=internal
+
+# External Auth Server URL (required if AUTH_MODE=external,
+# ignored if AUTH_MODE=internal)
+#
+# Examples:
+# - Demo auth server running locally: http://localhost:3001
+# - Auth0: https://your-tenant.auth0.com
+# - Okta: https://your-domain.okta.com
+#
+AUTH_SERVER_URL=http://localhost:3001
+
+# Redis Configuration (optional)
+# If not provided, session management will use in-memory storage
+# (sessions will be lost on server restart)
+#
+REDIS_URL=redis://localhost:6379
+REDIS_TLS=0
+
+# NODE_ENV controls Redis connection failure behavior:
+# - development: Continue running if Redis connection fails (with warning)
+# - production: Exit immediately if Redis connection fails
+NODE_ENV=development