[feat] One-click way to copy a terminal/chat pane's session ID in the UI #5108

Describe the feature

Add a quick, one-click way in the desktop UI to get/copy a terminal pane's session ID (the terminalId, and ideally the chatSessionId for chat panes).

Today there is no direct UI affordance to retrieve a session's ID. The closest existing feature is the Remote Control button's "Copy link", but that copies a shareable remote-control URL containing a remote-control sessionId (a separate concept) — not the terminal/chat session ID. The TerminalSessionDropdown displays the terminalId, but it isn't selectable or copyable.

Motivation

A terminal/chat session ID is the handle needed to communicate with or steer another session — e.g. building the deep link superset://v2-workspace/<workspaceId>?terminalId=<sessionId> (see #5029), or driving an existing session via CLI/MCP (see #4813). Right now you can't easily grab the ID of a session you're looking at, so handing one session's ID to another for cross-session coordination is awkward (hand-building URLs, digging through dropdowns, or guessing).

A small "Copy session ID" affordance closes that gap and makes the deep-linking (#5029) and CLI/MCP control (#4813) workflows usable from the UI.

Proposed UX

Any one (or more) of:

• A "Copy session ID" item in the terminal pane's header menu / TerminalHeaderExtras (next to the Remote Control button).
• A copy icon next to each session's terminalId in TerminalSessionDropdown.
• A command palette action, e.g. terminal.copySessionId, that copies the active pane's session ID.
• For chat panes, the equivalent for chatSessionId.

Nice-to-have: a menu option to copy the ready-to-open deep link (superset://v2-workspace/<workspaceId>?terminalId=<sessionId>) rather than just the raw ID.

Implementation pointers

• Terminal pane header extras: apps/desktop/src/renderer/routes/_authenticated/_dashboard/v2-workspace/$workspaceId/hooks/usePaneRegistry/components/TerminalPane/components/TerminalHeaderExtras/TerminalHeaderExtras.tsx
• Existing remote-control button (pattern + useCopyToClipboard usage): .../TerminalPane/components/TerminalRemoteControlButton/TerminalRemoteControlButton.tsx
• Session dropdown that already renders terminalId: .../TerminalPane/components/TerminalSessionDropdown/TerminalSessionDropdown.tsx

The useCopyToClipboard hook is already used in the remote-control button, so the clipboard plumbing exists.

Related

• Session deep-linking (chatSessionId/terminalId) is undocumented and not exposed by the CLI #5029 — Session deep-linking (chatSessionId/terminalId) is undocumented and not exposed by the CLI
• [feat] Expose controllable workspace terminal sessions via CLI/MCP #4813 — Expose controllable workspace terminal sessions via CLI/MCP
• CLI-created terminals not visible in Desktop UI: pty-daemon unaware of Drizzle ORM sessions #5103 — CLI-created terminals not visible in Desktop UI