feat(file-open): add Open Recent picker for recently opened files

[sinelaw]

Closes #926

What

Adds a recent-files feature: every user-initiated file open is recorded per window (most recent first, capped at 20) and persisted in the workspace file, so the list survives restarts.

The list is exposed through a new Open Recent action, reachable from:

• the File menu, right under "Open File..." ("Open Recent...")
• the command palette ("Open Recent")
• keybindings via the open_recent action string

It opens the standard fuzzy-filterable prompt picker (same pattern as Select Theme), pre-selected on the most recent entry. Selecting an entry opens it through the normal open-file path.

Design notes

• Recording happens in Editor::open_file — the user-initiated path. Session restore uses open_file_internal, so restoring a workspace doesn't scramble the recency order. Virtual/hidden buffers (panels, plugin UIs) are never recorded.
• Persistence is a new serde-defaulted recent_files field on the existing per-project Workspace struct, stored relative to the workspace root when possible (same convention as read_only_files). Older session files load unchanged.
• Edge cases: entries whose file was deleted are skipped when building the picker; an empty list shows a "No recent files" status message instead of an empty picker.
• A prompt picker was chosen over a dynamic File-menu submenu because generate_dynamic_items has no access to editor state (it only receives themes_dir), and threading window state through the menu expansion path (TUI + native macOS menus) would have been much more invasive. The picker also gives type-to-filter for free, which a commenter on the issue asked for.
• i18n keys added to all 14 locale files.

Testing

• 6 new e2e tests in tests/e2e/recent_files.rs: menu entry rendering, empty-list status message, list-and-open via palette, most-recent-first ordering, persistence across sessions, deleted-file skipping. All pass.
• Existing suites re-run green: workspace (51), command palette (75), menu (123) e2e tests, plus all 2725 fresh-editor lib tests.
• Manually validated in tmux: opened files, used File menu → Open Recent, picker ordering/filtering, re-open after restart with the same data dir — recent list persisted and reopened files correctly.

https://claude.ai/code/session_01DRkE5mej83XAHjmRMc3LSo

---

Generated by Claude Code