feat: folder scan, tab cleanup, repository shortcuts and an all-files…

[Sosakpanha]

… diff

Recent repositories gain a folder scan: pick a folder, the engine walks every folder under it (hidden and dependency folders skipped, nested repositories and submodules included) and a dialog lists what it found to add without opening. The owner's work folder holds 231 repositories, 198 of them five levels deep, so the recents list now keeps 1,000 entries instead of 30.

Tabs whose folder was moved or deleted close themselves with a note, and two open repositories that share a folder name show the nearest parent folder that tells them apart.

Cmd+P opens a search over every recent repository and switches to its tab when one is open, a new tab otherwise; Cmd+K alone opens the command palette now. Cmd+T opens a repository in a new tab like the + button.

The commit diff header gains a File / All files switch. All files stacks every changed file of the commit on one page with sticky collapsible headers, shared inline / side-by-side and view options, lazy loading, large files collapsed, and the inspector's file list kept in sync both ways.

What & why

Screenshots

Checklist

• pnpm typecheck && pnpm test pass
• cargo fmt --check && cargo clippy --all-targets -- -D warnings && cargo test pass (if Rust changed)
• New engine functions have integration tests in tests/git_engine.rs
• Mutating operations go through the undo tracked() wrapper where undoable
• Colors use design tokens only (no hex in components)
• CLAUDE.md updated if conventions/architecture changed
• Commits carry no trailers from coding tools (Co-authored-by: <tool>, Generated with …)