feat(migration): migrate legacy owner data and update config reference handling

- Implemented a migration process to move resources from the legacy owner "default" to the new default owner "local", ensuring no data loss during the transition.
- Updated configuration reference handling to replace legacy `$VAR_`, `$SECRET_`, and `$CONTEXT_` prefixes with mustache-style `{{ vars.name }}`, `{{ secrets.name }}`, and `{{ context.name }}`.
- Enhanced YAML configuration files and scripts to reflect the new mustache syntax, improving consistency across the application.
- Added tests to validate the migration process and ensure proper handling of legacy references.
- Updated documentation to guide users on the new configuration reference format.

examples/workflows/comic-monkeyuser-to-ntfy.yaml

@@ -1,6 +1,6 @@
 name: Comic - monkeyuser to ntfy
 description: |
-  Scrape the latest MonkeyUser comic and send it to ntfy (requires $VAR_ntfy_channel).
+  Scrape the latest MonkeyUser comic and send it to ntfy (requires {{ vars.ntfy_channel }}).
 scripts:
   - script: fetch-html.js
     config:
@@ -20,7 +20,7 @@ scripts:
   - script: fetch-binary.js
   - script: ntfy.js
     config:
-      url: $VAR_ntfy_channel
+      url: "{{ vars.ntfy_channel }}"
 triggers:
   - type: HTTP
     method: POST