Selective stashes

The Stash Manager can save all working-tree changes or only an explicitly reviewed set of changed files. Selected scope operates on whole paths: it does not imply partial-line selection, and the confirmation lists the exact files that will be passed to Git.

Paths are repository-relative, unique, and bounded to 500 entries and 64 KiB of aggregate path text. Absolute paths, traversal, controls, and paths outside the repository are rejected. Git receives paths after --, with no shell interpretation. The selected set is rechecked against working-directory state before creation.

Untracked and tracked changes follow Git's stash semantics shown by the review surface. An empty selection, unborn or conflicted repository, in-progress operation, changed selection, or Git failure leaves the working tree visible and reports that no reviewed stash was created.

Verification is in git/stash-test.ts (including a real selected-path fixture) and ui/stash-manager-test.tsx.