Repository sidebar and pinning

The repository sheet is a searchable workspace switcher rather than a flat recent list. It groups pinned repositories first, can show or hide the Recent group, and keeps account/provider/status filters independent so local-only, signed-out, and unavailable-account repositories are not misclassified.

Each row exposes repository status and a context menu for pin/unpin, local hide/unhide, editor, Explorer/Finder, and removal workflows. Hidden repositories remain registered and can be recovered through Show hidden; hiding never deletes a working tree or alters Git state. Missing or cloning repositories are labelled instead of being treated as clean.

Pin, group, alias, visibility, and filter settings are local UI metadata. Stable repository IDs prevent a path-label change from silently moving the setting to another repository. Switching uses the application's normal repository state guards and does not start a Git mutation.

Verification lives in repositories-list-grouping-test.ts, repository-list-visibility-test.ts, repository-list-context-menu-test.ts, and the repository-list filter/style suites.