Phase 4: Create standalone authorization server

- Created auth-server/index.ts with full OAuth endpoint support
- Reuses EverythingAuthProvider from main server
- Added custom /oauth/introspect endpoint for token validation
- Includes fake upstream auth routes for user authentication
- Added TypeScript configuration for auth server
- Added comprehensive npm scripts for all modes:
  - dev:integrated, dev:separate, dev:auth-server
  - dev:with-separate-auth (runs both servers)
  - build:auth-server, build:all
- Added concurrently dependency for running multiple servers
- Added detailed README for auth server
- Successfully serves OAuth metadata and health endpoints

auth-server/tsconfig.json

@@ -0,0 +1,9 @@
+{
+  "extends": "../tsconfig.json",
+  "compilerOptions": {
+    "outDir": "../dist/auth-server",
+    "rootDir": "../"
+  },
+  "include": ["index.ts", "../src/**/*.ts", "../shared/**/*.ts"],
+  "exclude": ["../dist", "../node_modules", "../**/*.test.ts"]
+}