feat: add React FieldRenderer system for settings and metaboxes

Complete React-based field rendering system that replaces WPCFTO Vue.js
layer while maintaining PHP field configuration compatibility.

Components:
- FieldRenderer: Main renderer with tabs support (metabox) and direct mode (settings)
- FieldTypes: 15+ field types (Text, Number, Select, Radio, Date, etc.)
- RepeaterField: Collapsible repeater with currency label parsing
- DependencyEngine: Show/hide fields based on conditions
- ValidationEngine: Client-side validation with error messages
- SettingsRenderer: Settings page with AJAX save to wp_options

Features:
- Repeater rows collapsed by default with readable currency titles
- Searchable dropdowns using Popover + Command pattern
- Proper label resolution for pre-selected values
- Hidden input sync for WordPress form submission

Also includes:
- FieldConfigBridge: Transform PHP configs to React format
- Updated Settings.php for React-based settings page
- Radio-group UI component
- wp-admin-restore.css for admin panel isolation

.gitignore

@@ -9,4 +9,17 @@ coverage
 *.ntvs*
 *.njsproj
 *.sln
-*.sw?node_modules/
+*.sw?
+
+# Build output
+build/
+
+# Development notes
+FINDINGS.md
+MIGRATION_STRATEGY.md
+TASKLIST.md
+docs/
+
+# npm
+package-lock.json
+node_modules/.package-lock.json