feat(log-tui): D on the worktrees view removes worktree + branch (#838)

[gfargo]

Closes #838.

Summary

Two delete actions in the worktrees view, with W keeping its existing semantics so muscle memory carries:

Key	Behavior
W (existing)	Remove worktree only. Leaves the branch in place for the user to re-attach later or delete separately from the branches view.
D (new)	Remove worktree and delete the branch it was tracking. Chains git worktree remove → git branch -d.

Both pre-flight guards inherit from the underlying helpers:

• removeWorktree refuses the current worktree and dirty worktrees.
• deleteBranch refuses the current branch and uses safe -d (so unmerged branches don't silently lose work).

Why per-view scoping for D

The global workflow-by-key dispatcher already routes D to delete-branch from anywhere in the TUI. Without per-view interception, pressing D on a worktree would silently target whatever was last cursored on the branches view rather than acting on the worktree under the cursor. The inkInput per-view scope (isWorktreeActionTarget(state) && context.worktreeListCount) catches D on the worktrees surface and routes it to the new remove-worktree-and-branch workflow before the global fallback sees it. From any other surface, D keeps doing what it always did.

Failure modes

• Worktree pre-flight fails (current / dirty): the chained action aborts before touching the branch. User sees the worktree-level error message.
• Branch delete fails (current branch / unmerged commits): the worktree was already removed; the user sees Removed worktree X, but branch delete failed: <git error>. Manual recovery: re-create the worktree if needed, then handle the branch separately.
• Detached HEAD (worktree had no branch): worktree removal succeeds, branch step is silently skipped with a (no branch to delete) success message.
• Branch missing from local refs (rare race): same skip-with-message path.

Test plan

• npm run lint
• npm run test:jest (1154 tests pass — added 5 new helper tests covering the happy path + partial-failure + 3 skip-the-branch-step paths, plus 4 input dispatch tests covering the per-view interception)
• npm run build
• npm run test:cli
• Manual: git worktree add ../foo feat/foo, coco ui, g w, cursor the new worktree, press D, confirm y, verify both the worktree directory and the feat/foo branch are gone

Follow-up (not in this PR)

The cross-surface case from the original issue (pressing D on a branch in the branches view that has an attached worktree fails) isn't fully closed. With the worktrees view as the canonical place to do worktree-lifecycle ops, the branches view's D could grow a clearer error pointing the user at "press g w then D". Left for a separate small PR if the new flow doesn't make the cross-surface confusion fade naturally.

🤖 Generated with Claude Code