Remove custom API endpoints in favor of Payload's native REST API

- Removed custom endpoint handler and endpoints directory
- Removed enableApi configuration option from plugin
- Updated client hooks to use Payload's native collection API
- Updated documentation to reflect API changes
- Updated view component to handle Payload API response format

The plugin now uses Payload CMS's built-in REST API for the feature-flags collection, which provides standard query syntax, pagination, and automatic access control enforcement.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

dev/payload.config.ts

@@ -127,7 +127,6 @@ export default buildConfig({
       // Enable all features
       enableRollouts: true,
       enableVariants: true,
-      enableApi: true,
       defaultValue: false,
 
       // Custom collection configuration