v0.7.0: Notewise-inspired UI + Math/Shape Tools + AI Overhaul

🎯 v0.7.0 — Notewise-inspired UI + Math/Shape Tools + AI Overhaul

🎨 UI Overhaul (Notewise-inspired, 100% original design)

• Pen Sub-Types: Fineliner (1px), Füller/Fountain (2.5px), Bleistift/Pencil (4px) via popup selector
• Shape Tools: Line, Arrow, Rectangle, Circle, Triangle, Freehand — dropdown from toolbar
• Color Palette: 5 quick-color dots + custom hex color picker
• Size Slider: Continuous 0.5–20px slider replaces 3 fixed dots
• Scratch-to-Erase: Toggle button for scratch gesture erasing
• AI Recognition: Direct toolbar button for OCR + Math recognition
• LaTeX Export: Copy to clipboard or export .tex file from Math panel

🧠 AI System (Complete Rewrite)

• OcrEngine: Florence-2 3-component pipeline (encoder/decoder/vision)
• GPU Detection: Auto-detect CUDA → DirectML → CPU fallback with GPU name
• 3-Tier Models: GPU-high (FP16), CPU-low (INT8), Medium — auto-selected
• BPE Tokenizer: Proper vocab.json/tokenizer.json loading, autoregressive decoding
• MathRecognizer: Stroke-based mathematical expression recognition
• LaTeXExporter: Full LaTeX document generation from recognized expressions

📐 Shape Features

• ShapeToolType Enum: Extended with Arrow, Triangle, Freehand
• ShapeHoldDetector: Draw+hold 500ms → auto-recognize shapes
• Shape Fill: 50% opacity fill for recognized shapes
• Circle-to-Lasso: Closed circle → select enclosed strokes

✏️ Text Recognition

• Smart Detection: Automatic math expression detection from OCR text
• MathEvaluator integration: evaluates arithmetic expressions
• Combined OCR + Math processing pipeline

🐛 Bug Fixes

• Paper/Dark-Mode: Paper is ALWAYS white — dark mode only affects UI
• Paper Lines: Always visible regardless of theme
• Template Switching: Now applies to ALL pages, not just current
• OnnxRuntime DLL conflict: DirectML package only (includes CPU fallback)
• 9 compiler warnings: All CS0067, CS0162, CS1998, CS8600, CS8618 resolved
• 5 async void → Task: Proper async patterns throughout
• 18 empty catch blocks: Now log via Debug.WriteLine
• ModelDownloader.cs: Removed (dead code with placeholder URLs)
• StylusTip.Illuminated: Fixed to StylusTip.Ellipse (WPF-compatible)
• ShapeToolType: Proper enum naming, Arrow/Triangle/Freehand added

⚙️ Technical

• Version bump: 0.6.0 → 0.7.0
• Microsoft.ML.OnnxRuntime.DirectML 1.21.0 (replaces base + GPU packages)
• Node.js 24 forced in GitHub Actions
• HttpClient timeout: 5 min for AutoUpdater, 30 min for ModelDownloader