Slug-based sharing and workspace sync improvements

Added(15)

• Added public share URLs using:
• /share/:username/:slug
• Improved share link stability and routing consistency
• Prevented slug collisions across renamed documents
• Improved loading and error handling for share services
• Surfaced localStorage save failures correctly
• Added loading text support for async button actions
• Added optional resume title support
• Improved title formatting and data handling consistency
• Removed deprecated storage and sync services
• Simplified workspace persistence architecture
• Improved maintainability across sync workflows
• Beta quality release
• Additional sync and sharing improvements expected
• Focused on workspace reliability, sharing consistency, and async UX enhancements