feat: Add presence heartbeat for Matrix online status

- matrix-gateway: POST /internal/matrix/presence/online endpoint
- usePresenceHeartbeat hook with activity tracking
- Auto away after 5 min inactivity
- Offline on page close/visibility change
- Integrated in MatrixChatRoom component

backend/services/wallet/wallet.interface.ts

@@ -0,0 +1,23 @@
+/**
+ * Wallet Service Interface
+ * Based on: core-services-mvp.md, updated for MicroDAO requirements
+ */
+
+import type { Balance } from '../../domain/wallet/types';
+
+export interface WalletService {
+  getBalances(userId: string): Promise<Balance[]>;
+  getDaarionBalance(userId: string): Promise<number>;
+  
+  // MicroDAO access checks (balance-based, no staking)
+  hasEnoughForMicroDaoCreate(userId: string): Promise<boolean>; // 1 DAARION
+  hasEnoughForAdminRole(userId: string): Promise<boolean>; // 1 DAARION
+  hasEnoughForMicroDaoUsage(userId: string): Promise<boolean>; // 0.01 DAARION
+  
+  // Legacy methods (deprecated)
+  hasEnoughForDaoCreate(userId: string): Promise<boolean>;
+  hasEnoughForVendorRegister(userId: string): Promise<boolean>;
+  hasEnoughForPlatformCreate(userId: string): Promise<boolean>;
+}
+
+