feat: Native Admin Bar QuickNav (Snippets) by DECKERWEB

[imantsk]

Summary

This PR brings a native Snippets QuickNav experience into Code Snippets via the WordPress Admin Bar. It adds a dedicated “Snippets” top-level admin bar menu with quick links plus paginated Active/Inactive snippet lists that update dynamically.

Credit

This work is based on the approach and UX established by “Snippets QuickNav” by David Decker – DECKERWEB (GitHub: @deckerweb):
https://github.com/deckerweb/snippets-quicknav
This PR implements the feature natively, following Code Snippets’ existing architecture and coding style.

What’s included

• Admin Bar → Snippets menu using the existing scissors icon (styled to better match WP admin bar icons)
• Main nodes:
  • Manage
  • Add New
  • Import
  • Settings
  • Active Snippets
  • Inactive Snippets
• Active/Inactive lists:
  • Show snippet titles prefixed with type, e.g. (PHP) My snippet title (type inferred from type)
  • Paginate when the list exceeds the configured limit
  • Pagination controls live at the top of the submenu and fetch pages via the Snippets REST API
• Safe Mode
  • Safe Mode indicator shows only when Safe Mode is active
  • Adds a Safe Mode docs link as a submenu item: https://snipco.de/safe-mode (opens in new tab, uses Dashicons)
• Free vs Pro gating
  • Pro-only “Add New” types (CSS/JS/Conditions) are greyed out in free and link to the upgrade page

Settings added

• Toggle to enable/disable the admin bar menu (default: enabled)
• “Snippets per page in Admin Bar” (default: 20)

How to test

1. Go to Code Snippets settings and confirm Admin Bar QuickNav is enabled; set the per-page limit to something small (e.g. 5).
2. Open the WP Admin Bar → Snippets and verify the main nodes and submenu structure.
3. Open Active Snippets / Inactive Snippets and click pagination controls; confirm the list updates correctly.
4. Enable Safe Mode and confirm the Safe Mode indicator appears and the Safe Mode docs submenu link opens in a new tab.