Update quality-playbook skill to v1.5.6 + add agent (#1402)

Rebuilds branch from upstream/staged (was previously merged from
upstream/main, which brought in materialized plugin files that
fail Check Plugin Structure on PRs targeting staged).

Changes vs. staged:
- Update skills/quality-playbook/ to v1.5.6 (31 bundled assets:
  SKILL.md + LICENSE.txt + 16 references/ + 9 phase_prompts/ +
  3 agents/ + bin/citation_verifier.py + quality_gate.py).
- Add agents/quality-playbook.agent.md (top-level orchestrator).
  name: quality-playbook (validator-compliant).
- Update docs/README.skills.md quality-playbook row description
  + bundled-assets list to v1.5.6.
- Fix 'unparseable' → 'unparsable' in quality_gate.py (5 instances;
  codespell preference, both spellings valid).

Closes the v1.4.0 → v1.5.6 update in a single clean commit on top of
upstream/staged. The preserved backup branch backup-bedbe84-pre-rebuild
(SHA bedbe848fa3c0f0eda8e653c42b599a17dd2e354) holds the prior history for reference.

docs/README.skills.md

@@ -290,7 +290,7 @@ See [CONTRIBUTING.md](../CONTRIBUTING.md#adding-skills) for guidelines on how to
 | [qdrant-scaling](../skills/qdrant-scaling/SKILL.md)<br />`gh skills install github/awesome-copilot qdrant-scaling` | Guides Qdrant scaling decisions. Use when someone asks 'how many nodes do I need', 'data doesn't fit on one node', 'need more throughput', 'cluster is slow', 'too many tenants', 'vertical or horizontal', 'how to shard', or 'need to add capacity'. | `minimize-latency`<br />`scaling-data-volume`<br />`scaling-qps`<br />`scaling-query-volume` |
 | [qdrant-search-quality](../skills/qdrant-search-quality/SKILL.md)<br />`gh skills install github/awesome-copilot qdrant-search-quality` | Diagnoses and improves Qdrant search relevance. Use when someone reports 'search results are bad', 'wrong results', 'low precision', 'low recall', 'irrelevant matches', 'missing expected results', or asks 'how to improve search quality?', 'which embedding model?', 'should I use hybrid search?', 'should I use reranking?'. Also use when search quality degrades after quantization, model change, or data growth. | `diagnosis`<br />`search-strategies` |
 | [qdrant-version-upgrade](../skills/qdrant-version-upgrade/SKILL.md)<br />`gh skills install github/awesome-copilot qdrant-version-upgrade` | Guidance on how to upgrade your Qdrant version without interrupting the availability of your application and ensuring data integrity. | None |
-| [quality-playbook](../skills/quality-playbook/SKILL.md)<br />`gh skills install github/awesome-copilot quality-playbook` | Explore any codebase from scratch and generate six quality artifacts: a quality constitution (QUALITY.md), spec-traced functional tests, a code review protocol with regression test generation, an integration testing protocol, a multi-model spec audit (Council of Three), and an AI bootstrap file (AGENTS.md). Includes state machine completeness analysis and missing safeguard detection. Works with any language (Python, Java, Scala, TypeScript, Go, Rust, etc.). Use this skill whenever the user asks to set up a quality playbook, generate functional tests from specifications, create a quality constitution, build testing protocols, audit code against specs, or establish a repeatable quality system for a project. Also trigger when the user mentions 'quality playbook', 'spec audit', 'Council of Three', 'fitness-to-purpose', 'coverage theater', or wants to go beyond basic test generation to build a full quality system grounded in their actual codebase. | `LICENSE.txt`<br />`references/constitution.md`<br />`references/defensive_patterns.md`<br />`references/functional_tests.md`<br />`references/review_protocols.md`<br />`references/schema_mapping.md`<br />`references/spec_audit.md`<br />`references/verification.md` |
+| [quality-playbook](../skills/quality-playbook/SKILL.md)<br />`gh skills install github/awesome-copilot quality-playbook` | Run a complete quality engineering audit on any codebase. Derives behavioral requirements from the code, generates spec-traced functional tests, runs a three-pass code review with regression tests, executes a multi-model spec audit (Council of Three), and produces a consolidated bug report with TDD-verified patches. Finds the 35% of real defects that structural code review alone cannot catch. Works with any language. Trigger on 'quality playbook', 'spec audit', 'Council of Three', 'fitness-to-purpose', or 'coverage theater'. | `LICENSE.txt`<br />`agents`<br />`phase_prompts`<br />`quality_gate.py`<br />`references/challenge_gate.md`<br />`references/code-only-mode.md`<br />`references/constitution.md`<br />`references/defensive_patterns.md`<br />`references/exploration_patterns.md`<br />`references/functional_tests.md`<br />`references/iteration.md`<br />`references/orchestrator_protocol.md`<br />`references/requirements_pipeline.md`<br />`references/requirements_refinement.md`<br />`references/requirements_review.md`<br />`references/review_protocols.md`<br />`references/run_state_schema.md`<br />`references/schema_mapping.md`<br />`references/spec_audit.md`<br />`references/verification.md` |
 | [quasi-coder](../skills/quasi-coder/SKILL.md)<br />`gh skills install github/awesome-copilot quasi-coder` | Expert 10x engineer skill for interpreting and implementing code from shorthand, quasi-code, and natural language descriptions. Use when collaborators provide incomplete code snippets, pseudo-code, or descriptions with potential typos or incorrect terminology. Excels at translating non-technical or semi-technical descriptions into production-quality code. | None |
 | [react-audit-grep-patterns](../skills/react-audit-grep-patterns/SKILL.md)<br />`gh skills install github/awesome-copilot react-audit-grep-patterns` | Provides the complete, verified grep scan command library for auditing React codebases before a React 18.3.1 or React 19 upgrade. Use this skill whenever running a migration audit - for both the react18-auditor and react19-auditor agents. Contains every grep pattern needed to find deprecated APIs, removed APIs, unsafe lifecycle methods, batching vulnerabilities, test file issues, dependency conflicts, and React 19 specific removals. Always use this skill when writing audit scan commands - do not rely on memory for grep syntax, especially for the multi-line async setState patterns which require context flags. | `references/dep-scans.md`<br />`references/react18-scans.md`<br />`references/react19-scans.md`<br />`references/test-scans.md` |
 | [react18-batching-patterns](../skills/react18-batching-patterns/SKILL.md)<br />`gh skills install github/awesome-copilot react18-batching-patterns` | Provides exact patterns for diagnosing and fixing automatic batching regressions in React 18 class components. Use this skill whenever a class component has multiple setState calls in an async method, inside setTimeout, inside a Promise .then() or .catch(), or in a native event handler. Use it before writing any flushSync call - the decision tree here prevents unnecessary flushSync overuse. Also use this skill when fixing test failures caused by intermediate state assertions that break after React 18 upgrade. | `references/batching-categories.md`<br />`references/flushSync-guide.md` |