Implement Dashboard with system stats (Phase 11 P1)

Dashboard Features:
- Dashboard.vue: System overview UI
- System stats: CPU, Memory, Disk usage
- Service status: SMB/SFTP/WebDAV/Backup
- Recent activity log

Tauri Commands:
- get_system_stats: CPU/Memory/Disk stats (macOS + Linux)
- get_all_services_status: Service status list
- get_recent_activity: Activity log

Platform Support:
- macOS: top + vm_stat + df commands
- Linux: /proc/stat + /proc/meminfo + df

UI Components:
- CPU usage progress bar (color-coded)
- Memory usage progress bar
- Disk usage progress bar
- Service status table
- Quick actions buttons
- Recent activity table

Router:
- Added /dashboard route

Home.vue:
- Added Dashboard card (first card)

Build: ✅ Tauri + markbase-core
Tests: 495 markbase-core + 201 smb-server

markbase-tauri/src-tauri/src/main.rs

@@ -52,6 +52,9 @@ fn main() {
             update_share,
             delete_share,
             test_share_connection,
+            get_system_stats,
+            get_all_services_status,
+            get_recent_activity,
         ])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");