feat: add marketplace skills as local project skills

Move skill definitions from the nanoclaw-skills marketplace plugin
into .claude/skills/ so they're available as unprefixed slash commands
(e.g. /add-whatsapp instead of /nanoclaw-skills:add-whatsapp).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.claude/skills/add-pdf-reader/SKILL.md

@@ -0,0 +1,100 @@
+---
+name: add-pdf-reader
+description: Add PDF reading to NanoClaw agents. Extracts text from PDFs via pdftotext CLI. Handles WhatsApp attachments, URLs, and local files.
+---
+
+# Add PDF Reader
+
+Adds PDF reading capability to all container agents using poppler-utils (pdftotext/pdfinfo). PDFs sent as WhatsApp attachments are auto-downloaded to the group workspace.
+
+## Phase 1: Pre-flight
+
+1. Check if `container/skills/pdf-reader/pdf-reader` exists — skip to Phase 3 if already applied
+2. Confirm WhatsApp is installed first (`skill/whatsapp` merged). This skill modifies WhatsApp channel files.
+
+## Phase 2: Apply Code Changes
+
+### Ensure WhatsApp fork remote
+
+```bash
+git remote -v
+```
+
+If `whatsapp` is missing, add it:
+
+```bash
+git remote add whatsapp https://github.com/qwibitai/nanoclaw-whatsapp.git
+```
+
+### Merge the skill branch
+
+```bash
+git fetch whatsapp skill/pdf-reader
+git merge whatsapp/skill/pdf-reader
+```
+
+This merges in:
+- `container/skills/pdf-reader/SKILL.md` (agent-facing documentation)
+- `container/skills/pdf-reader/pdf-reader` (CLI script)
+- `poppler-utils` in `container/Dockerfile`
+- PDF attachment download in `src/channels/whatsapp.ts`
+- PDF tests in `src/channels/whatsapp.test.ts`
+
+If the merge reports conflicts, resolve them by reading the conflicted files and understanding the intent of both sides.
+
+### Validate
+
+```bash
+npm run build
+npx vitest run src/channels/whatsapp.test.ts
+```
+
+### Rebuild container
+
+```bash
+./container/build.sh
+```
+
+### Restart service
+
+```bash
+launchctl kickstart -k gui/$(id -u)/com.nanoclaw  # macOS
+# Linux: systemctl --user restart nanoclaw
+```
+
+## Phase 3: Verify
+
+### Test PDF extraction
+
+Send a PDF file in any registered WhatsApp chat. The agent should:
+1. Download the PDF to `attachments/`
+2. Respond acknowledging the PDF
+3. Be able to extract text when asked
+
+### Test URL fetching
+
+Ask the agent to read a PDF from a URL. It should use `pdf-reader fetch <url>`.
+
+### Check logs if needed
+
+```bash
+tail -f logs/nanoclaw.log | grep -i pdf
+```
+
+Look for:
+- `Downloaded PDF attachment` — successful download
+- `Failed to download PDF attachment` — media download issue
+
+## Troubleshooting
+
+### Agent says pdf-reader command not found
+
+Container needs rebuilding. Run `./container/build.sh` and restart the service.
+
+### PDF text extraction is empty
+
+The PDF may be scanned (image-based). pdftotext only handles text-based PDFs. Consider using the agent-browser to open the PDF visually instead.
+
+### WhatsApp PDF not detected
+
+Verify the message has `documentMessage` with `mimetype: application/pdf`. Some file-sharing apps send PDFs as generic files without the correct mimetype.