fix: harden v1 lease recovery

[frueda-godaddy]

Summary

• Persist new slot/lease intent before materializing a worktree so interrupted acquire can be repaired instead of disappearing during heal.
• Quarantine failed postCreate/preRelease hook transitions and persist structured diagnostics.failedPhase instead of relying on hook error message prefixes.
• Replay postCreate during resume-acquire when the failed pending acquire did not complete its creation hook, and cover preRelease replay during resume-cleanup.
• Require explicit branch reuse through SDK/CLI, with --reuse-existing-branch as the opt-in path; document repair-time branch reuse semantics.
• Add reset-release slot reuse coverage and tune Vitest worker/timeouts for the git/process-heavy suite.

Review follow-up

Addressed review nits from the approve-with-nits pass:

• Replaced string-based postCreate replay heuristic with structured failedPhase.
• Added resume-cleanup after preRelease hook failure regression.
• Added acquire -> reset release -> second acquire clean slot regression.
• Updated README fail-first branch creation example and repair reuse note.
• Added comment for intentional postAcquire non-quarantine behavior.
• Replaced review-noted err: any catches in pool.ts and git/branch.ts.

Verification

• pnpm lint
• pnpm build
• pnpm typecheck
• pnpm exec vitest run packages/grove/test/transitions.test.ts packages/grove/test/lease.integration.test.ts -t "structured|postCreate|preRelease|reset release returns a clean slot" --reporter=verbose
• pnpm exec vitest run --reporter=verbose (12 files, 145 tests passed)

Note: direct push to ferueda/grove is not available to the active GitHub account, so this PR is opened from the frueda-godaddy/grove fork.