feat(reference-curator): Add portable skill suite for reference documentation curation

6 modular skills for curating, processing, and exporting reference docs:
- reference-discovery: Search and validate authoritative sources
- web-crawler-orchestrator: Multi-backend crawling (Firecrawl/Node/aiohttp/Scrapy)
- content-repository: MySQL storage with version tracking
- content-distiller: Summarization and key concept extraction
- quality-reviewer: QA loop with approve/refactor/research routing
- markdown-exporter: Structured output for Claude Projects or fine-tuning

Cross-machine installation support:
- Environment-based config (~/.reference-curator.env)
- Commands tracked in repo, symlinked during install
- install.sh with --minimal, --check, --uninstall modes
- Firecrawl MCP as default (always available)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

custom-skills/90-reference-curator/05-quality-reviewer/code/CLAUDE.md

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+# Quality Reviewer
+
+QA loop for reference library content. Scores distilled materials, routes decisions, and provides actionable feedback.
+
+## Trigger Keywords
+"review content", "quality check", "QA review", "assess distilled content", "check reference quality"
+
+## Decision Flow
+
+```
+[Distilled Content]
+       │
+       ▼
+┌─────────────────┐
+│ Score Criteria  │ → accuracy, completeness, clarity, PE quality, usability
+└─────────────────┘
+       │
+       ├── ≥ 0.85 → APPROVE → markdown-exporter
+       ├── 0.60-0.84 → REFACTOR → content-distiller
+       ├── 0.40-0.59 → DEEP_RESEARCH → web-crawler
+       └── < 0.40 → REJECT → archive
+```
+
+## Scoring Criteria
+
+| Criterion | Weight | Checks |
+|-----------|--------|--------|
+| **Accuracy** | 0.25 | Factual correctness, up-to-date, attribution |
+| **Completeness** | 0.20 | Key concepts, examples, edge cases |
+| **Clarity** | 0.20 | Structure, concise language, logical flow |
+| **PE Quality** | 0.25 | Techniques, before/after, explains why |
+| **Usability** | 0.10 | Easy reference, searchable, appropriate length |
+
+## Workflow
+
+### Step 1: Load Pending Reviews
+```bash
+python scripts/load_pending_reviews.py --output pending.json
+```
+
+### Step 2: Score Content
+```bash
+python scripts/score_content.py --distill-id 123 --output assessment.json
+```
+
+### Step 3: Calculate Final Score
+```bash
+python scripts/calculate_score.py --assessment assessment.json
+```
+
+### Step 4: Route Decision
+```bash
+python scripts/route_decision.py --distill-id 123 --score 0.78
+```
+
+Outputs:
+- `approve` → Ready for export
+- `refactor` → Return to distiller with instructions
+- `deep_research` → Need more sources (queries generated)
+- `reject` → Archive with reason
+
+### Step 5: Log Review
+```bash
+python scripts/log_review.py --distill-id 123 --decision refactor --instructions "Add more examples"
+```
+
+## PE Quality Checklist
+
+When scoring `prompt_engineering_quality`:
+- [ ] Demonstrates specific techniques (CoT, few-shot, etc.)
+- [ ] Shows before/after examples
+- [ ] Explains *why* techniques work
+- [ ] Provides actionable patterns
+- [ ] Includes edge cases and failure modes
+- [ ] References authoritative sources
+
+## Auto-Approve Rules
+
+Tier 1 sources with score ≥ 0.80 may auto-approve:
+```yaml
+# In config
+quality:
+  auto_approve_tier1_sources: true
+  auto_approve_min_score: 0.80
+```
+
+## Scripts
+
+- `scripts/load_pending_reviews.py` - Get pending reviews
+- `scripts/score_content.py` - Multi-criteria scoring
+- `scripts/calculate_score.py` - Weighted average calculation
+- `scripts/route_decision.py` - Decision routing logic
+- `scripts/log_review.py` - Log review to database
+- `scripts/generate_feedback.py` - Generate refactor instructions
+
+## Integration
+
+| From | Action | To |
+|------|--------|-----|
+| content-distiller | Distilled content | → |
+| → | APPROVE | markdown-exporter |
+| → | REFACTOR + instructions | content-distiller |
+| → | DEEP_RESEARCH + queries | web-crawler-orchestrator |