✨ feat(admin): add user data dashboard for cross-project data visualization

Add comprehensive admin dashboard to view and manage user data across all projects:

Backend:
- Add admin endpoints to Chat, Todo, Contacts, Calendar, Picture, Zitare, Presi
- Each backend exposes GET/DELETE /api/v1/admin/user-data/:userId
- Service-to-service auth via X-Service-Key header

Aggregation (mana-core-auth):
- GET /api/v1/admin/users - Paginated user list with search
- GET /api/v1/admin/users/:userId/data - Aggregated data from all backends
- DELETE /api/v1/admin/users/:userId/data - GDPR deletion across all projects

Frontend (ManaCore web):
- New User Data tab in admin navigation
- User search page at /admin/user-data
- User detail page with ProjectDataCard components
- GDPR deletion dialog with email confirmation

Presi:
- Migrate user_id from UUID to TEXT for Better Auth compatibility
- Add SQL migration script

services/mana-core-auth/src/admin/dto/user-data.dto.ts

@@ -0,0 +1,78 @@
+export interface EntityCount {
+	entity: string;
+	count: number;
+	label: string;
+}
+
+export interface ProjectDataSummary {
+	projectId: string;
+	projectName: string;
+	icon: string;
+	available: boolean;
+	error?: string;
+	entities: EntityCount[];
+	totalCount: number;
+	lastActivityAt?: string;
+}
+
+export interface UserDataSummary {
+	user: {
+		id: string;
+		email: string;
+		name: string;
+		role: string;
+		createdAt: string;
+		emailVerified: boolean;
+	};
+	auth: {
+		sessionsCount: number;
+		accountsCount: number;
+		has2FA: boolean;
+		lastLoginAt: string | null;
+	};
+	credits: {
+		balance: number;
+		totalEarned: number;
+		totalSpent: number;
+		transactionsCount: number;
+	};
+	projects: ProjectDataSummary[];
+	totals: {
+		totalEntities: number;
+		projectsWithData: number;
+	};
+}
+
+export interface DeleteUserDataResponse {
+	success: boolean;
+	deletedFromProjects: {
+		projectId: string;
+		projectName: string;
+		success: boolean;
+		error?: string;
+		deletedCount?: number;
+	}[];
+	deletedFromAuth: {
+		sessions: number;
+		accounts: number;
+		credits: number;
+		user: boolean;
+	};
+	totalDeleted: number;
+}
+
+export interface UserListItem {
+	id: string;
+	email: string;
+	name: string;
+	role: string;
+	createdAt: string;
+	lastActiveAt?: string;
+}
+
+export interface UserListResponse {
+	users: UserListItem[];
+	total: number;
+	page: number;
+	limit: number;
+}