feat(ssh): duplicate saved hosts from context menu

[WilliamWang1721]

Result / 用户结果

SSH Settings saved-host rows now expose the existing SSH actions through a right-click menu: Connect, Edit, Copy, and Delete.

Copy opens a new-host draft prefilled from the selected host, reusing the existing SSH editor/profile loading path. The copied display name uses the existing label allocator (for example, Alpha → Alpha 1, then Alpha 2). The destination field is intentionally cleared because Pebrel currently uses the destination itself as the persisted host identity; the user only needs to enter the new target and adjust any other differing fields.

Design / 设计边界

• Reuses the existing GPUI context-menu component and existing Connect/Edit/Delete behavior.
• Reuses open_ssh_editor for copying auth mode, keys, icon, port, proxy/jump settings and organization metadata; no second SSH editor or persistence path.
• Reuses SshProfiles::next_default_label for collision-free copy names.
• No persisted-format, dependency, threading or host-identity changes.
• Stored secrets remain in the OS credential store and are not copied into editor text fields, preserving the existing no-secret-backfill contract.
• No new shortcut was introduced because these host-scoped launcher/settings actions currently have no existing effective key binding to reuse.

Evidence / 验证依据

• Branch starts directly from current upstream main (9dc058d12765893553d5fc7a2c37c870c96168b0).
• Added a focused GPUI regression assertion covering copy-draft identity, cleared destination and generated Alpha 1 label.
• Full repository CI is requested by opening this PR Ready for Review.

Required Review / 必须确认

• Focused single-purpose change; no duplicate persistence authority.
• No architecture budget, dependency, workflow or governance changes.
• Existing typed menu messages are reused; no new translation catalog entries.
• No defensive framework or unrelated refactor added.

UI Review Screenshots

Current-head evidence for d5181c983e37ad0642fb2dea52560bee1d9af047. UI review workflow run

Windows — success

Raw evidence: Windows originals

macOS — success

Raw evidence: macOS originals

[Kuddev]

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CI?https://github.com/Kuddev/pebrel/actions/runs/36161534274