Release v1.16.0: install handoff skill, add publish skill, sync upstream

- Make plan2code-handoff an installed workflow prompt: move to src/,
  register in install.js SOURCE_PROMPTS, remove repo-local-only copy
- Add repo-local maintainer /plan2code-publish skill (cuts GitHub Releases;
  excluded from install.js)
- Review workflow next-step suggestion made context-aware (upstream v1.15.4)
- Doc updates: list handoff in README, QUICK-REFERENCE, architecture table;
  add "Adding a New Workflow Prompt / Skill" checklist to dev-commands
- Fix broken AGENTS.md index links: rename .agents-docs loop/metrics files
  to plan2code-* to match references
- Bump version.json to 1.16.0 to align with package.json and CHANGELOG

.agents-docs/AGENTS-plan2code-metrics.md

@@ -0,0 +1,82 @@
+# Plan2Code Metrics
+> Part of [AGENTS.md](../AGENTS.md) — project guidance for AI coding agents.
+
+A recursive self-improvement toolchain for plan2code contributors. Collects run metrics, aggregates by prompt generation, diagnoses weak steps via AI, and proposes surgical prompt edits.
+
+## Metrics Data Flow
+
+```
+Collect → Aggregate → Analyze → Improve → Apply
+```
+
+1. **Collector** reads project artifacts (`specs/<feature>/`) → writes `RunMetrics` JSON per run
+2. **Aggregator** groups runs by prompt SHA fingerprint (cohorts) → `aggregated.json`
+3. **Analyzer** invokes AI with aggregated metrics + prompt contents → diagnosis markdown
+4. **Improver** invokes AI with diagnosis → validated `PromptEdit[]` proposals (char limit + verbatim checks)
+5. **Applier** shows interactive diffs → patches `src/plan2code-*.md` files
+
+## Metrics Commands
+
+```bash
+cd plan2code-metrics && npm run build  # Build the CLI
+plan2code-metrics                      # Run (fully interactive, no flags)
+```
+
+## Metrics CLI Menu
+
+| Option | Action |
+|--------|--------|
+| Collect | Read spec artifacts → run JSON |
+| Import | Copy run JSON from another project |
+| View | Display cohort metrics with health indicators |
+| Analyze | AI diagnosis of weak metrics |
+| Propose | AI improvement proposals with validation |
+| Apply | Interactive diff review + file patching |
+
+## Key Source Files
+
+| File | Purpose |
+|------|---------|
+| `types.ts` | All interfaces (`RunMetrics`, `UserFeedback`, `CohortMetrics`, etc.) + `METRIC_TARGETS` |
+| `collector.ts` | Reads project artifacts → run JSON (parses plan drafts, overview.md, loop logs) |
+| `aggregator.ts` | Merges runs by prompt generation (SHA cohort) → `aggregated.json` |
+| `analyzer.ts` | AI diagnosis via `prompts/analyze.md` template |
+| `improver.ts` | AI proposals via `prompts/improve.md` + validation (char count, old_text match) |
+| `applier.ts` | Interactive diff review + file patching |
+| `cli.ts` | Menu-driven interactive CLI (100% prompts, no flags) |
+| `invoke-llm.ts` | Unified LLM interface (Claude Code or Copilot CLI) |
+
+## User Feedback
+
+The collector parses an optional `## User Feedback` table from `overview.md`:
+
+```markdown
+## User Feedback
+| Field | Value |
+|-------|-------|
+| Rating | 8 |
+| Reason | Smooth workflow |
+| Went Well | Planning was thorough |
+| Went Poorly | Some tasks unclear |
+```
+
+Feedback is collected during finalize (Step 5) or retroactively via the CLI. Pipe characters in values are escaped as `\|`. The aggregator computes `avg_user_rating` and `feedback_count` per cohort.
+
+## Supported AI Agents
+
+- **Claude Code** (recommended): `claude` CLI with `--inputFile` for prompt delivery
+- **GitHub Copilot CLI**: `copilot` CLI with stdin prompt delivery
+
+## Metric Targets
+
+| Metric | Target | Direction |
+|--------|--------|-----------|
+| `avg_confidence` | ≥ 90 | higher is better |
+| `avg_task_completion_rate` | ≥ 0.95 | higher is better |
+| `avg_blocker_count` | ≤ 1.5 | lower is better |
+| `avg_completion_marker_success_rate` | ≥ 0.95 | higher is better |
+| `avg_verification_failures_found` | ≤ 1.0 | lower is better |
+| `archival_success_rate` | ≥ 0.99 | higher is better |
+| `avg_user_rating` | ≥ 7.0 | higher is better |
+
+Data stored in `.plan2code-metrics/` (runs/, aggregated.json, proposals/).