Extract auth module: standalone PocketBase OAuth2 + Graph token management

- Create reusable auth-module/ with frontend and backend components
- Frontend: PocketBaseAuth class for OAuth2 login and token management
- Backend: GraphTokenManager and PocketBaseValidator for token operations
- Includes TypeScript types and comprehensive README
- No project-specific dependencies - ready to use in other projects

auth-module/types.ts

@@ -0,0 +1,53 @@
+/**
+ * Frontend Auth Configuration
+ */
+export interface AuthConfig {
+  pbUrl?: string;
+  collection?: string;
+  provider?: string;
+  loginContainerId?: string;
+  userDisplayNameId?: string;
+  userEmailId?: string;
+  loginBtnId?: string;
+  loginErrorId?: string;
+}
+
+/**
+ * Backend Auth Configuration
+ */
+export interface BackendAuthConfig {
+  clientId?: string;
+  tenantId?: string;
+  clientSecret?: string;
+}
+
+/**
+ * Auth state object
+ */
+export interface AuthState {
+  isAuthenticated: boolean;
+  user: {
+    id: string;
+    name: string;
+    email: string;
+  } | null;
+  token: string | null;
+}
+
+/**
+ * Graph token cache object
+ */
+export interface GraphTokenCache {
+  token: string;
+  expiresOn: number;
+}
+
+/**
+ * Auth event callbacks
+ */
+export interface AuthCallbacks {
+  onAuthSuccess?: (state: AuthState) => void;
+  onAuthFailure?: (error: any) => void;
+  onTokenUpdate?: (state: AuthState) => void;
+  onUiUpdate?: (state: AuthState) => void;
+}