feat(desktop): add Rename Session menu shortcut

[anduimagui]

Issue for this PR

Closes #1389

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Adds desktop support for renaming sessions via menu shortcut.

• Adds File > Rename Session... in packages/desktop/src/menu.ts
• Uses accelerator Shift+Cmd+E on macOS
• Triggers app command id session.rename through desktop command wiring
• Adds i18n key desktop.menu.file.renameSession in packages/desktop/src/i18n/en.ts

On current dev, session.rename was not registered yet. This PR includes minimal app command registration in packages/app/src/pages/session/message-timeline.tsx and reuses the existing inline title editor.

Related:

• feat(tui): make dialog keybinds configurable (#6143) #6144
• [Enhancement] Add configurable keybinds for dialog actions (#6144) #6143
• Feature Request: Rename Session Title #1389
• Restore ability to rename sessions #3655
• Session rename (via /rename or /session + ctrl-r) not working #3779
• /rename command unreachable - fuzzy search does not filter command list [OpenCode version: 1.1.25] #9471
• feat(app): add session search and rename functionality #6973
• feat(tui): add Ctrl+R prompt history search #12307
• feat(opencode): add click to rename session in TUI sidebar #13243

How did you verify your code works?

• Verified in desktop app:
  • File > Rename Session... appears
  • Shift+Cmd+E triggers session title rename flow
• CI on this PR: typecheck and unit checks pass

Screenshots / recordings

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

If you do not follow this template your PR will be automatically rejected.

[github-actions]

Thanks for updating your PR! It now meets our contributing guidelines. 👍