feat: reorganize admin settings with tabbed interface and documentation

- Reorganized admin settings into tabbed interface (General, Security, Payment Methods)
- Vertical tabs on desktop, horizontal scrollable on mobile
- Moved Payment Methods from separate menu to Settings tab
- Fixed admin profile reuse and dashboard blocking
- Fixed maintenance mode guard to use AppConfig model
- Added admin auto-redirect after login (admins → /admin, users → /)
- Reorganized documentation into docs/ folder structure
- Created comprehensive README and documentation index
- Added PWA and Web Push notifications to to-do list

apps/api/dist/common/guards/maintenance.guard.d.ts

@@ -0,0 +1,11 @@
+import { CanActivate, ExecutionContext } from '@nestjs/common';
+import { Reflector } from '@nestjs/core';
+import { PrismaService } from '../../prisma/prisma.service';
+import { JwtService } from '@nestjs/jwt';
+export declare class MaintenanceGuard implements CanActivate {
+    private reflector;
+    private prisma;
+    private jwtService;
+    constructor(reflector: Reflector, prisma: PrismaService, jwtService: JwtService);
+    canActivate(context: ExecutionContext): Promise<boolean>;
+}