feat(skills): bulk-add root SKILL.md to 61 skills (native Agent Skills loadability)

Run the additive migration pass from SKILL-MIGRATION-GUIDE: generate a root SKILL.md
for every skill that lacked one, copied from its desktop/SKILL.md (or code/SKILL.md),
with name set to the directory name and description + body preserved verbatim.

- scripts/migrate_skill_root.py: the reusable, non-destructive migrator (dry-run default).
- 61 new root SKILL.md (desktop source for most; code/SKILL.md for 61/62/92).
- Untouched: 16/17/95 (already had root); desktop/ and code/ packaging left intact.
- All 64 root SKILL.md validate: frontmatter <=1024, kebab name, description present.

Still MANUAL (no SKILL.md source — commands/README only), need hand-authored root SKILL.md:
81-mac-optimizer, 90-reference-curator, 91-multi-agent-guide, 94-dintel-bootstrap.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

custom-skills/53-notebooklm-research/SKILL.md

@@ -0,0 +1,144 @@
+---
+name: 53-notebooklm-research
+description: |
+  Research and source discovery for NotebookLM. Web/Drive research, auto-import, and source text extraction.
+  Triggers: research topic, find sources, web research, 리서치, 자료 조사, NotebookLM 연구.
+---
+
+# NotebookLM Research
+
+Research workflows for NotebookLM: web research, Drive search, auto-import, and source content extraction.
+
+## Prerequisites
+
+```bash
+pip install notebooklm-py
+playwright install chromium
+notebooklm login
+```
+
+## When This Skill Activates
+
+- "Research [topic] in NotebookLM"
+- "Find sources about X"
+- "Do web research on Y"
+- "Search my Drive for documents"
+- Korean: "리서치 해줘", "자료 찾아줘", "웹 검색"
+
+## Research Modes
+
+| Mode | Sources Found | Time | Use Case |
+|------|---------------|------|----------|
+| `fast` | 5-10 | seconds | Quick overview |
+| `deep` | 20+ | 2-5 min | Comprehensive research |
+
+## Quick Reference
+
+### Web Research
+
+```bash
+# Fast research (default)
+notebooklm source add-research "artificial intelligence trends"
+
+# Deep research with auto-import
+notebooklm source add-research "climate change policy" --mode deep --import-all
+
+# Deep research (non-blocking, wait separately)
+notebooklm source add-research "topic" --mode deep --no-wait
+notebooklm research wait --import-all
+```
+
+### Drive Research
+
+```bash
+# Search Google Drive
+notebooklm source add-research "quarterly report" --from drive
+
+# Deep Drive search
+notebooklm source add-research "project docs" --from drive --mode deep
+```
+
+### Research Status
+
+```bash
+# Check ongoing research
+notebooklm research status
+
+# Wait for completion
+notebooklm research wait
+notebooklm research wait --import-all  # Auto-import found sources
+```
+
+## Source Content Extraction
+
+```bash
+# Get indexed fulltext
+notebooklm source fulltext <source_id>
+notebooklm source fulltext <source_id> --json
+
+# Get AI-generated guide
+notebooklm source guide <source_id>
+```
+
+## Workflow: Research to Analysis
+
+```bash
+# 1. Create notebook
+notebooklm create "AI Research Project"
+
+# 2. Run deep research
+notebooklm source add-research "large language models 2024" --mode deep --no-wait
+
+# 3. Wait and import (can spawn subagent for this)
+notebooklm research wait --import-all
+
+# 4. Verify sources
+notebooklm source list
+
+# 5. Start analysis
+notebooklm ask "What are the key trends?"
+```
+
+## Subagent Pattern for Deep Research
+
+For non-blocking deep research:
+
+```python
+# Main conversation
+notebooklm source add-research "topic" --mode deep --no-wait
+
+# Spawn subagent to wait
+Task(
+  prompt="Wait for research in notebook {id} and import sources.
+          Use: notebooklm research wait -n {id} --import-all --timeout 300
+          Report how many sources were imported.",
+  subagent_type="general-purpose"
+)
+```
+
+## Autonomy Rules
+
+**Auto-run:**
+- `notebooklm research status`
+- `notebooklm source list`
+- `notebooklm source fulltext`
+- `notebooklm source guide`
+
+**Ask first:**
+- `notebooklm source add-research` (modifies notebook)
+- `notebooklm research wait --import-all` (long-running)
+
+## Tips
+
+1. **Use deep mode** for comprehensive research
+2. **Use --no-wait** for non-blocking operations
+3. **Spawn subagent** for long waits
+4. **Check research status** before importing
+
+## Error Handling
+
+| Error | Solution |
+|-------|----------|
+| No results | Try different keywords |
+| Timeout | Extend timeout or check status |
+| Rate limit | Wait and retry |