docs: Refactor README to clarify Core features vs UI components

Major changes:
- Remove "Pro" branding from core features - all features except UI are now part of core package
- Clarify that only UI components are separate packages published to npm
- Remove AI-powered features from documentation (not fully implemented)
- Remove License Management section (not a required feature)
- Update all code examples to use MediaUploader instead of MediaUploaderPro
- Add comprehensive npm publishing instructions for UI components (@mediaman/vue, @mediaman/react, @mediaman/core)
- Simplify comparison table with Spatie to include all core features
- Remove separate "Core vs Pro" comparison table
- Update section headers: "MediaMan Pro Features" → "Advanced Features"
- Reorganize UI Components as a standalone section with installation guide

All features are now part of the core MediaMan package:
- UUID support, versioning, tagging, batch operations
- Rate limiting, query caching, monitoring & logging
- Advanced image processing, security features
- Database indexes, API documentation

UI components remain separate npm packages for framework-specific usage.

Author: claude