feat: add authentication, user management, and admin features

Added comprehensive authentication and authorization system:

Authentication System:
- Better Auth integration with session management
- Login/logout pages and API routes
- Middleware for route protection
- Auth utilities and client libraries

User Management:
- User list, detail, and invite pages
- User API endpoints (CRUD operations)
- Session management for users
- Profile settings page

Role-Based Access Control:
- Role management pages (list, create, edit)
- Permission system with granular controls
- Role assignment to users
- Role API endpoints

Admin Features:
- Audit log page for tracking system events
- Admin settings page
- Audit service for logging user actions

Additional Features:
- Quotes management pages and components
- SalesBldr API integration
- Email service for notifications

Configuration & Documentation:
- Updated docker-compose.yml
- MCP server configuration (mcp.json)
- CVE-2025-55182 security review documentation
- Standards guide and PRD documents
- Re-enabling authentication documentation

Database Migrations:
- 012: Auth tables (users, sessions, accounts, verifications)
- 013: Role tables (roles, permissions, role_permissions, user_roles)
- 014: Admin settings table

UI Updates:
- Updated dashboard layout
- Enhanced app layout with auth integration

lib/auth-client.ts

@@ -0,0 +1,40 @@
+import { createAuthClient } from "better-auth/react";
+import { magicLinkClient, twoFactorClient, adminClient } from "better-auth/client/plugins";
+import { ac, adminRole, userRole, superAdminRole } from "./permissions";
+
+export const authClient = createAuthClient({
+  baseURL: process.env.NEXT_PUBLIC_BETTER_AUTH_URL || "",
+  plugins: [
+    // Magic link client
+    magicLinkClient(),
+
+    // Two-factor authentication client
+    twoFactorClient({
+      onTwoFactorRedirect() {
+        window.location.href = "/auth/2fa";
+      },
+    }),
+
+    // Admin client with RBAC
+    adminClient({
+      ac,
+      roles: {
+        "super-admin": superAdminRole,
+        admin: adminRole,
+        user: userRole,
+      },
+    }),
+  ],
+});
+
+// Export commonly used hooks and methods
+export const {
+  signIn,
+  signOut,
+  useSession,
+  getSession,
+} = authClient;
+
+// Type exports
+export type Session = typeof authClient.$Infer.Session;
+export type User = typeof authClient.$Infer.Session.user;