recent_projects: Connect on Enter from a remote host header

[aanyberg]

The host header row was inert, so searching for a host and pressing Enter did nothing - users had to arrow down to the "Open Folder" row. Make the header a selectable confirm target that connects and opens the remote folder chooser, mirroring "Open Folder". Both paths now share a single open_folder_for_server helper, and the footer shows an "Open Folder" button when a header is selected.

Objective

In the remote server picker, searching for a host and pressing Enter did nothing — the host header row was inert, so users had to arrow down to the "Open Folder" row to connect. This makes the header row behave like a real confirm target.

• Fixes Remote SSH: pressing enter on host header should connect and present folder selector #60092

Solution

• RemoteMatch::ServerHeader is now selectable (is_selectable only excludes Separator), so search + Enter lands on it and confirm connects.
• Extracted a shared RemoteServerPickerDelegate::open_folder_for_server helper (via a small FolderConnectTarget enum) so both the header row and the existing "Open Folder" row drive the exact same connect-and-open-folder flow - persisted SSH connections reuse their ServerIndex, and ssh-config-only hosts are first persisted via create_host_from_ssh_config.
• The header row now renders a selected/highlighted background state, and the footer shows an "Open Folder" confirm button when a header row is selected.

Testing

• Added unit tests covering RemoteMatch::is_selectable and folder_connect_target's routing for persisted vs. ssh-config-only entries.
• Added gpui::tests verifying that searching a host selects its header (not a stale project row beneath it) and that an ssh-config-only host's header is selectable and followed by its "Open Folder" row.
• Ran cargo test -p recent_projects --lib remote_servers - all 19 tests pass.
• Manually verified: open the remote server picker, type part of a host name, press Enter — it now connects and opens the folder picker instead of being a no-op.

Self-Review Checklist:

• I've reviewed my own diff for quality, security, and reliability
• Unsafe blocks (if any) have justifying comments
• The content adheres to Zed's UI standards (UX/UI and icon guidelines)
• Tests cover the new/changed behavior
• Performance impact has been considered and is acceptable

Showcase

Click to view showcase

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Release Notes:

• Fixed pressing Enter on a remote host search result doing nothing instead of connecting

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[aanyberg]

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