Add Docker support and improve PDF conversion

Features:
- Dockerfile for containerized deployment
- Docker Compose configuration with health checks
- Automated database initialization via entrypoint script
- Quick start script for easy Docker deployment
- Comprehensive Docker deployment documentation (DOCKER.md)
- Complete README with installation and usage instructions
- .dockerignore for optimized image builds

Improvements:
- PDF conversion now preserves orientation (portrait/landscape)
- PDF rendering at 300 DPI for sharp quality
- Maintains aspect ratio during conversion
- Compact media library view with image thumbnails
- Better media preview with scrollable gallery

Docker Features:
- Multi-stage build for smaller images
- Non-root user for security
- Health checks for container monitoring
- Volume mounts for persistent data
- Production-ready Gunicorn configuration
- Support for Redis caching (optional)

app/blueprints/content.py

@@ -308,12 +308,11 @@ def process_pdf_file(filepath: str, filename: str) -> tuple[bool, str]:
         
         log_action('info', f'Converting PDF to images: {filename}')
         
-        # Convert PDF pages to images at Full HD resolution
+        # Convert PDF pages to images at high DPI for quality
         images = convert_from_path(
             filepath,
-            dpi=150,  # Good quality for Full HD display
-            fmt='png',
-            size=(1920, 1080)  # Direct Full HD output
+            dpi=300,  # 300 DPI for sharp rendering
+            fmt='png'
         )
         
         if not images:
@@ -323,18 +322,34 @@ def process_pdf_file(filepath: str, filename: str) -> tuple[bool, str]:
         base_filename = Path(filename).stem
         upload_folder = os.path.dirname(filepath)
         
-        # Save each page directly as PNG
+        # Save each page with proper aspect ratio preservation
         converted_files = []
         for idx, image in enumerate(images, start=1):
             # Create filename for this page
             page_filename = f"{base_filename}_page{idx:03d}.png"
             page_filepath = os.path.join(upload_folder, page_filename)
             
-            # Save the image directly without additional optimization
-            image.save(page_filepath, 'PNG', optimize=True)
+            # Determine orientation and resize maintaining aspect ratio
+            width, height = image.size
+            is_portrait = height > width
+            
+            # Define Full HD dimensions based on orientation
+            if is_portrait:
+                # Portrait: max height 1920, max width 1080 (rotated Full HD)
+                max_size = (1080, 1920)
+            else:
+                # Landscape: max width 1920, max height 1080 (standard Full HD)
+                max_size = (1920, 1080)
+            
+            # Resize maintaining aspect ratio (thumbnail maintains ratio)
+            from PIL import Image as PILImage
+            image.thumbnail(max_size, PILImage.Resampling.LANCZOS)
+            
+            # Save the optimized image
+            image.save(page_filepath, 'PNG', optimize=True, quality=95)
             
             converted_files.append((page_filepath, page_filename))
-            log_action('info', f'Converted PDF page {idx}/{len(images)}: {page_filename}')
+            log_action('info', f'Converted PDF page {idx}/{len(images)} ({width}x{height} -> {image.size[0]}x{image.size[1]}): {page_filename}')
         
         log_action('info', f'PDF converted successfully: {len(images)} pages from {filename}')