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-voice-transcription/SKILL.md

@@ -0,0 +1,144 @@
+---
+name: add-voice-transcription
+description: Add voice message transcription to NanoClaw using OpenAI's Whisper API. Automatically transcribes WhatsApp voice notes so the agent can read and respond to them.
+---
+
+# Add Voice Transcription
+
+This skill adds automatic voice message transcription to NanoClaw's WhatsApp channel using OpenAI's Whisper API. When a voice note arrives, it is downloaded, transcribed, and delivered to the agent as `[Voice: <transcript>]`.
+
+## Phase 1: Pre-flight
+
+### Check if already applied
+
+Check if `src/transcription.ts` exists. If it does, skip to Phase 3 (Configure). The code changes are already in place.
+
+### Ask the user
+
+Use `AskUserQuestion` to collect information:
+
+AskUserQuestion: Do you have an OpenAI API key for Whisper transcription?
+
+If yes, collect it now. If no, direct them to create one at https://platform.openai.com/api-keys.
+
+## Phase 2: Apply Code Changes
+
+**Prerequisite:** WhatsApp must be installed first (`skill/whatsapp` merged). This skill modifies WhatsApp channel files.
+
+### 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/voice-transcription
+git merge whatsapp/skill/voice-transcription
+```
+
+This merges in:
+- `src/transcription.ts` (voice transcription module using OpenAI Whisper)
+- Voice handling in `src/channels/whatsapp.ts` (isVoiceMessage check, transcribeAudioMessage call)
+- Transcription tests in `src/channels/whatsapp.test.ts`
+- `openai` npm dependency in `package.json`
+- `OPENAI_API_KEY` in `.env.example`
+
+If the merge reports conflicts, resolve them by reading the conflicted files and understanding the intent of both sides.
+
+### Validate code changes
+
+```bash
+npm install --legacy-peer-deps
+npm run build
+npx vitest run src/channels/whatsapp.test.ts
+```
+
+All tests must pass and build must be clean before proceeding.
+
+## Phase 3: Configure
+
+### Get OpenAI API key (if needed)
+
+If the user doesn't have an API key:
+
+> I need you to create an OpenAI API key:
+>
+> 1. Go to https://platform.openai.com/api-keys
+> 2. Click "Create new secret key"
+> 3. Give it a name (e.g., "NanoClaw Transcription")
+> 4. Copy the key (starts with `sk-`)
+>
+> Cost: ~$0.006 per minute of audio (~$0.003 per typical 30-second voice note)
+
+Wait for the user to provide the key.
+
+### Add to environment
+
+Add to `.env`:
+
+```bash
+OPENAI_API_KEY=<their-key>
+```
+
+Sync to container environment:
+
+```bash
+mkdir -p data/env && cp .env data/env/env
+```
+
+The container reads environment from `data/env/env`, not `.env` directly.
+
+### Build and restart
+
+```bash
+npm run build
+launchctl kickstart -k gui/$(id -u)/com.nanoclaw  # macOS
+# Linux: systemctl --user restart nanoclaw
+```
+
+## Phase 4: Verify
+
+### Test with a voice note
+
+Tell the user:
+
+> Send a voice note in any registered WhatsApp chat. The agent should receive it as `[Voice: <transcript>]` and respond to its content.
+
+### Check logs if needed
+
+```bash
+tail -f logs/nanoclaw.log | grep -i voice
+```
+
+Look for:
+- `Transcribed voice message` — successful transcription with character count
+- `OPENAI_API_KEY not set` — key missing from `.env`
+- `OpenAI transcription failed` — API error (check key validity, billing)
+- `Failed to download audio message` — media download issue
+
+## Troubleshooting
+
+### Voice notes show "[Voice Message - transcription unavailable]"
+
+1. Check `OPENAI_API_KEY` is set in `.env` AND synced to `data/env/env`
+2. Verify key works: `curl -s https://api.openai.com/v1/models -H "Authorization: Bearer $OPENAI_API_KEY" | head -c 200`
+3. Check OpenAI billing — Whisper requires a funded account
+
+### Voice notes show "[Voice Message - transcription failed]"
+
+Check logs for the specific error. Common causes:
+- Network timeout — transient, will work on next message
+- Invalid API key — regenerate at https://platform.openai.com/api-keys
+- Rate limiting — wait and retry
+
+### Agent doesn't respond to voice notes
+
+Verify the chat is registered and the agent is running. Voice transcription only runs for registered groups.