Add agentic delivery contract

[WalksWithASwagger]

Summary

• Add a repo-local agentic/contract.json with the standard ready/review/stop labels, provider policy, diff limits, branch pattern, Linear project metadata, and verification commands.
• Add GitHub Actions for issue quality, noop/command-provider dev loop execution, and acceptance-criteria PR review.
• Add the provider adapter, repo doctor/status scripts, agentic-intake command, docs, and focused tests.
• Harden the delivery guardrails so staged tracked changes count toward diff limits before PR creation.

Safety

• v1 opens PRs only; it never auto-merges.
• noop is the default provider, so real execution stays disabled until repo variables/secrets are set after a workflow-dispatch dry run.
• PR review only auto-runs for codex/issue-*, codex/BC-*, or codex/bc-* agent output branches, so rollout/maintenance branches are not mislabeled.
• The runner refuses pause signals, stop labels, dirty worktrees, failed verification, and diffs over 20 files or 500 changed lines.

Verification

• venv/bin/python -m pytest tests/agentic -q -> 15 passed after rebase on current main
• venv/bin/python -m py_compile scripts/agentic/*.py
• YAML parse for agentic workflows
• python3 scripts/agentic/ensure_labels.py --dry-run
• python3 -m json.tool agentic/contract.json
• git diff --check

Follow-up After Merge

• Run the Agentic Dev Loop workflow manually with provider noop before enabling a real provider secret.

[WalksWithASwagger]

PR-review follow-up landed in f6e0e2d. It switches the contract verification command to one that exists on this PR's current base (python3 -m pytest tests/agentic -q) and fixes changed_stats so staged tracked changes count toward PR/no-PR and diff-limit decisions. Verification: agentic tests -> 15 passed, py_compile, workflow YAML parse, ensure_labels dry-run, json.tool, diff-check.