fix(storage): remove Windows worktrees outside their cwd

[liugddx]

Summary

• execute the final git worktree remove from the stable Git common directory
• avoid asking a Windows Git process to delete its own current working directory
• preserve existing clean, detach, Host lease branch deletion, and repository allocation semantics

Closes two failures tracked by #2142:

• retires only the Host lease branch after a child switches branches
• recovery preserves live bindings and retires orphaned worktrees

Validation

• @maka/storage build
• both affected tests pass in three consecutive Windows runs (6/6)
• Biome format check
• git diff --check

The complete test file separately observed a temp-root cleanup EBUSY in an unrelated availability test. This PR does not add broad filesystem retries or claim to address that independent cleanup failure.

[jackwener]

Adversarial review — approve & merge

Root cause

runGit uses git -C <cwd> …, and Git chdirs into that path. On Windows, a process cannot delete its own current directory, so:

git -C <worktree> worktree remove --force <worktree>

fails when removing the worktree that is the process cwd.

Fix

Keep clean / detach / lease-branch delete on the worktree (they need the checkout), then run only the final:

git -C <gitCommonDir> worktree remove --force <path>

gitCommonDir is the resolved absolute common dir (realpath of --git-common-dir), already used for repository allocation serialization — outside the worktree being deleted.

Checked

Concern	Result
Correct Git context	git -C <commonDir> is a valid repo entry point; verified worktree remove from common dir works
Path identity	Same absolute path as before; registration path from provision unchanged
Ordering / semantics	clean → detach → clean → branch -D → remove preserved
Lease branch only	Child-switched branches still preserved (existing test)
Orphan recovery	Uses inspected.gitCommonDir; same call path
Allocation lock	Still under withRepositoryAllocation(gitCommonDir)
Injection	execFile argv array; no shell
Partial failure	Pre-existing: branch may be deleted if remove fails mid-way — not introduced
Unix regression	Superset behavior; POSIX still fine (cwd restriction is Windows-specific)

Validation

• CI green including windows_baseline
• Local: both named tests pass after rebuild

No blocking issues. LGTM.