[Feature] Thêm tính năng VNC, export và import danh sách thiết bị

[thanhphv]

Problem Statement

Proposed Solution

Alternatives Considered

Additional Context

[thangnm93]

Status update

Breaking the three bundled requests down against the current codebase:

Import device list — ✅ largely done

Bulk host import already ships with broad format coverage in import_panel.dart:
~/.ssh/config, CSV, PuTTY, MobaXterm, SecureCRT, Ansible inventory, WinSCP, Termius, and SSH URI — plus QR / P2P LAN sync. No further work needed unless a new source format is requested.

Export device list — ⚠️ partial

Only per-host export exists today (_ExportDialog: .ssh/config and JSON for a single host). There is no whole-list / bulk export to a file yet. This is the remaining gap on the export side.

VNC support — ❌ not started

No VNC code exists. Only RDP is implemented (the yourssh_rdp Rust crate). VNC would be a new protocol track, structurally similar to the RDP integration.

Suggested next steps

This issue bundles three independent features. Recommend keeping it as a tracking parent and splitting into focused issues so each can land on its own PR:

• Full host-list (bulk) export — JSON + .ssh/config
• VNC protocol support (new client, mirroring the RDP architecture)

Import is effectively complete and can be checked off.