docs: restructure README with concise overview and improved organization
- Condensed README from 715 to 113 lines with streamlined feature descriptions
- Replaced verbose documentation with quick-start focused content
- Reorganized sections: removed detailed architecture, API endpoints, and Meilisearch implementation details
- Added version badges and simplified feature categories (Navigation, Markdown, Graph)
- Streamlined installation instructions with Docker-first approach and simplified local
feat: enhance Unsplash integration with pagination, random images, and portrait orientation
- Added pagination support to search endpoint with page parameter and orientation control (defaults to portrait)
- Implemented new /random endpoint for fetching random portrait images with configurable count
- Enhanced UnsplashPickerComponent with infinite scroll, loading states, and automatic random image loading on open
- Added debounced search input, scroll detection for pagination, and improved error
refactor: compact block context menu styling and improve visual density
- Reduced menu width from 240px to 220px and decreased padding throughout for more compact layout
- Scaled down button sizes (p-2 → p-1.5), gaps (gap-3 → gap-2.5), and font sizes (text-base → text-sm)
- Shrunk color picker swatches from 7x7 to 5x5 with thinner ring borders for cleaner appearance
- Tightened spacing in toolbars, submenus, and all menu sections while maintaining usability
- Added opacity property binding
feat: add collapsible block type and enhance paragraph menu UX
- Added CollapsibleBlockComponent with registration in block host and columns
- Enhanced paragraph block with inline "+" button for column layouts and improved menu positioning
- Updated toggle block to support creating new toggle blocks below with dedicated event handlers
- Improved menu styling with fixed positioning, keyboard navigation (arrows, Enter, Escape), and focus management
- Simplified inline action handling by deleg
feat: add file block with drag-and-drop support
- Implemented file upload block with preview support for images, videos, PDFs, text, code, and DOCX files
- Added drag-and-drop directive for files with visual drop indicators in root and column contexts
- Created file icon component with FontAwesome integration for 50+ file type icons
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- Replaced emoji icons with consistent SVG icons for checkbox, bullet, and numbered lists in context menu and inline toolbar
- Enhanced drag-drop visual feedback with subtle highlight on target blocks during dragging
- Refined column creation logic to use deterministic drop modes (column-left, column-right, column-gap) for more predictable behavior
- Improved comment button z-index to prevent overlap with drag indicators
- Replaced generic alignment buttons with custom image-specific icons (left/center/right/full width)
- Added "Default size" button to reset image dimensions and aspect ratio
- Implemented modal dialogs for image info and caption editing to replace browser prompts
- Enhanced lateral drop detection to create 2-column layouts when dragging blocks side-by-side
- Integrated Unsplash API for image search functionality with environment configuration
- Added new Nimbus Editor page component with navigation from sidebar and mobile drawer
- Enhanced TOC with highlight animation for editor heading navigation
- Improved CDK overlay z-index hierarchy for proper menu layering
- Removed obsolete logging validation script
