chore: remove archived taskgrind directory and tooling

[fyodoriv]

Why needed

The taskgrind/ directory (overnight-autonomous-session prompt template, enforcement scripts, and README) has been archived/extracted, so its files, task entries, and cross-doc references are now dead weight in the spec repo. Removing them keeps tasks.md focused on the TASKS.md spec and its small reference packages.

What changed

• Removed the taskgrind/ directory: README.md, prompt-template.md, and the four enforcement scripts (check-admin-merge-rate.mjs, check-zero-ship-streak.mjs, lint-pr-shape.mjs, safe-admin-merge.sh).
• Removed taskgrind references from AGENTS.md, README.md, ROADMAP.md, spec.md, and the PR template.
• Removed the archived taskgrind task entries from TASKS.md.
• Integrated latest main (github-issues backend, spec.md § Task backends, VISION G5) — merged cleanly with no conflicts.

Vision trace

• Vision goal: "Spec first, packages second" (VISION.md § Strategy, G1) — removing archived auxiliary tooling keeps the reference packages small and the repo spec-focused.
• User story: N/A — archived-tooling removal, no user-facing story
• Competitor prior art: N/A — internal repo cleanup, no comparable spec

How to test manually

npm run build
npm test
npm run lint
npx -y @tasks-md/lint TASKS.md
node packages/cli/dist/cli.js generate-commands && git diff --exit-code commands/

Verification

• npm run build — pass
• npm test — pass (480 tests: cli 209, lint 62, mcp 125, parser 84)
• npm run lint — pass (TASKS.md 0 errors; examples/ 0 errors; commands-drift clean)

Rollback

git revert <merge-commit>

Pure removal of archived tooling plus a clean merge of main; revert restores the taskgrind/ files and references. No spec-version implications.

---

🤖 Written by an agent, not Fyodor. Ping me if this looks off.