feat: WebGPU Backend, UI Overhaul, and Performance Optimizations

[sergeyplis]

Description: This PR introduces a major upgrade to BrainChop, integrating a WebGPU backend for accelerated inference, refreshing the UI/UX, and significantly optimizing performance and memory usage for large models.

Key Changes
🚀 WebGPU & Inference Backend

• WebGPU Support: Implemented a full WebGPU backend for faster client-side inference. Huge thanks to @spikedoanz and @wpmed92
• Smart Fallback: Added logic to automatically attempt progressively "safer" execution modes (WebGPU → WebGL) to ensure stability across devices.
• Universal Runners: Standardized runners to handle both WebGL and WebGPU contexts seamlessly.
• Backend Indicator: Added a visual indicator in the UI to show which backend is currently active.

⚡ Performance & Optimization

• Faster Normalization: Optimized Quantile Normalization to use sampling, significantly reducing pre-processing time.
• WebGL Memory Management: Improved memory estimation and implemented a "chunked argmax" strategy. This allows large models (e.g., 104-class, 50-class) to run on standard WebGL backends without memory crashes.
• Stability: Fixed memory leaks to improve reliability during repeated drag-and-drop operations.

🎨 UI/UX Improvements

• Visual Overhaul: Comprehensive CSS updates, harmonizing toolbar styles, fonts, and spacing.
• About Section: Added a new "About" window detailing privacy (local processing), keyboard shortcuts (C for Clip, V for View), and model icon legends.
• Streamlined Interface: Removed the "Clip Plane" checkbox in favor of the 'C' keyboard shortcut to declutter the UI.
• Visualization: Enforced specific colormaps (Copper) for brain extraction/masking models.

🛠️ Infrastructure & Diagnostics

• Unified Diagnostics: Centralized diagnostic logging for both WebGL and WebGPU to assist in debugging.
• Deployment Fixes: Resolved pathing issues (favicon, relative paths) for GitHub Pages deployment.
• Console Logging: Enabled better console output in production builds for easier troubleshooting.