Scale the pipeline: enforced lanes, resumable runs, browser QA, backlog, CI

[TMKAB121]

Hard enforcement (converts CLAUDE.md's deferred hardening note into mechanics):

• .claude/hooks/enforce-lanes.js: PreToolUse hook denying Write/Edit outside
  each agent's lane, package.json/lockfiles/node_modules for everyone, and
  subagent edits to the enforcement layer; Bash heuristics block package
  managers and git commit/push for subagents. Fails open on internal errors.
• .claude/hooks/check-footer.js: SubagentStop hook requiring the handoff footer.
• .claude/settings.json: hook registration + package-manager deny rules.

Throughput:

• All four agents pinned to model: sonnet so runs don't inherit a pricier
  session model.
• /feature Phases 4 & 6 now batch defects/findings by Area — one invocation
  per dev agent, parallel when both have work.
• /feature Phase 0 writes docs/pipeline/NNN-.md state after every phase;
  new /feature-resume continues interrupted runs; SessionStart hook surfaces
  in-flight runs and queued backlog items.
• New /backlog command + docs/backlog.md convention: feature queue that
  doubles as the spec-number registry for concurrent runs.

Capability:

• tools/browser.js: zero-dependency headless-Chromium wrapper (dom | shot).
  QA captures rendered evidence into docs/qa/evidence/NNN-/; the
  ux-designer verifies design against the screenshots, not just source.
  Defect template gains an Evidence field.
• .github/workflows/ci.yml: node --test suite + zero-dependency audit +
  design-token audit on push/PR.

Docs: CLAUDE.md (commands, workflow rules, artifact conventions, rewritten
Enforcement note) and README (lane enforcement, multi-feature/worktree
guidance, updated adoption guide and repo layout).

Co-Authored-By: Claude Fable 5 noreply@anthropic.com
Claude-Session: https://claude.ai/code/session_01Vh1iYgAxqnvbBy1sPNtGPD