feat: Add mobile CI/CD secrets setup for APK signing

- Updated Makefile to include new command for setting up mobile CI secrets.
- Enhanced tools.mk with setup-mobile-ci-secrets target.
- Created setup-mobile-github-secrets.sh script for configuring GitHub Secrets for APK signing.
- Added APK signing implementation summary documentation.
- Created detailed APK signing setup guide.
- Added GitHub secrets checklist for easy reference.

docs/RELEASE/GITHUB_SECRETS_CHECKLIST.md

@@ -0,0 +1,115 @@
+# GitHub Secrets Checklist for APK Signing
+
+**Quick reference for repository secret configuration**
+
+📍 **Configure at**: Repository Settings → Secrets and variables → Actions
+
+---
+
+## ✅ Worker Mobile (Staff App) - 12 Secrets
+
+### Dev Environment
+- [ ] `WORKER_KEYSTORE_DEV_BASE64`
+- [ ] `WORKER_KEYSTORE_PASSWORD_DEV`
+- [ ] `WORKER_KEY_ALIAS_DEV` 
+- [ ] `WORKER_KEY_PASSWORD_DEV`
+
+### Staging Environment
+- [ ] `WORKER_KEYSTORE_STAGING_BASE64`
+- [ ] `WORKER_KEYSTORE_PASSWORD_STAGING`
+- [ ] `WORKER_KEY_ALIAS_STAGING`
+- [ ] `WORKER_KEY_PASSWORD_STAGING`
+
+### Production Environment
+- [ ] `WORKER_KEYSTORE_PROD_BASE64`
+- [ ] `WORKER_KEYSTORE_PASSWORD_PROD`
+- [ ] `WORKER_KEY_ALIAS_PROD`
+- [ ] `WORKER_KEY_PASSWORD_PROD`
+
+---
+
+## ✅ Client Mobile - 12 Secrets
+
+### Dev Environment
+- [ ] `CLIENT_KEYSTORE_DEV_BASE64`
+- [ ] `CLIENT_KEYSTORE_PASSWORD_DEV`
+- [ ] `CLIENT_KEY_ALIAS_DEV`
+- [ ] `CLIENT_KEY_PASSWORD_DEV`
+
+### Staging Environment
+- [ ] `CLIENT_KEYSTORE_STAGING_BASE64`
+- [ ] `CLIENT_KEYSTORE_PASSWORD_STAGING`
+- [ ] `CLIENT_KEY_ALIAS_STAGING`
+- [ ] `CLIENT_KEY_PASSWORD_STAGING`
+
+### Production Environment
+- [ ] `CLIENT_KEYSTORE_PROD_BASE64`
+- [ ] `CLIENT_KEYSTORE_PASSWORD_PROD`
+- [ ] `CLIENT_KEY_ALIAS_PROD`
+- [ ] `CLIENT_KEY_PASSWORD_PROD`
+
+---
+
+## 📦 Total: 24 Secrets
+
+**Status**: ⬜ Not Started | 🟡 In Progress | ✅ Complete
+
+---
+
+## 🔧 Quick Setup Commands
+
+### Generate base64 for existing keystores:
+
+```bash
+# Worker Mobile Dev (already in repo)
+base64 -i apps/mobile/apps/staff/android/app/krow_with_us_staff_dev.jks
+
+# Client Mobile Dev (already in repo)
+base64 -i apps/mobile/apps/client/android/app/krow_with_us_client_dev.jks
+
+# For staging/prod keystores (retrieve from secure storage first):
+base64 -i /path/to/krow_staff_staging.jks
+base64 -i /path/to/krow_staff_prod.jks
+base64 -i /path/to/krow_client_staging.jks
+base64 -i /path/to/krow_client_prod.jks
+```
+
+### Or use the helper script:
+
+```bash
+.github/scripts/setup-mobile-github-secrets.sh
+```
+
+---
+
+## 📋 Dev Environment Values (Public - Already in Repo)
+
+**Worker Mobile:**
+- Password: `krowwithus`
+- Alias: `krow_staff_dev`
+- Key Password: `krowwithus`
+- Keystore: `apps/mobile/apps/staff/android/app/krow_with_us_staff_dev.jks`
+
+**Client Mobile:**
+- Password: `krowwithus`
+- Alias: `krow_client_dev`
+- Key Password: `krowwithus`
+- Keystore: `apps/mobile/apps/client/android/app/krow_with_us_client_dev.jks`
+
+---
+
+## 🚨 Important Notes
+
+1. **Staging/Production keystores** should NEVER be committed to the repository
+2. Retrieve staging/prod keystores from:
+   - CodeMagic Team Settings → Code signing identities
+   - Or your organization's secure key management system
+3. Keep keystore passwords in a password manager
+4. Test with **dev environment first** before configuring staging/prod
+
+---
+
+## 📚 Related Documentation
+
+- [Complete Setup Guide](./APK_SIGNING_SETUP.md)
+- [Release Workflow](./MOBILE_RELEASE_PLAN.md)