feat(lastcode): resume after quick ci

[lastobelus]

Quick CI was still blocking every agent push and rebase for roughly 9–10 minutes in its old form, even though GitHub CI now owns comprehensive PR validation. That repeated local wait was the largest uncovered polling burden in the LastCode delivery workflow.

This trims Quick CI to exact branch-diff whitespace checks, format/lint, and workspace typechecking. It adds an independent resumable Project Action that records a receipt bound to the exact head, current local origin/lastcode/main, and gate version. The pre-push hook accepts only a matching receipt for refs at the checked-out head; ordinary command-line pushes without one still run the same gate synchronously. The action never pushes, and dirty worktrees, head/base changes, validation failures, or gate revisions cannot reuse stale results.

Measured trimmed duration was about 43–45 seconds after package preparation, projecting to roughly 4.6 polling turns per ordinary PR and 6.6 per complex PR at the observed usage frequency. The implementation dogfooded its exact command and receipt: Quick CI passed for 6e16b5cf2 against 953b281a4, and the real pre-push hook reused that receipt in 3.3 seconds.

Tracking: #103

Implemented by GPT-5.6-SOL via the Codex harness in LastCode.