FRE-606: Add icon generation and tests for Tauri desktop

- Add generate-icons.sh script for cross-platform icon generation
- Generate all required icon sizes (32x32, 128x128, 256x256, 512x512)
- Create Windows .ico and macOS .icns icons
- Add Rust unit tests for core functionality
- Add tauri:test and tauri:icons npm scripts

New files:
- src-tauri/generate-icons.sh
- src-tauri/icons/32x32.png
- src-tauri/icons/128x128.png
- src-tauri/icons/128x128@2x.png
- src-tauri/icons/512x512.png
- src-tauri/icons/icon.ico
- src-tauri/icons/icon.icns
- src-tauri/icons/src/app-icon.svg
- src-tauri/icons/tray-icon.png
- src-tauri/src/tests.rs

Modified:
- src-tauri/src/lib.rs (added tests module)

src-tauri/generate-icons.sh

@@ -0,0 +1,87 @@
+#!/bin/bash
+# Icon generation script for Tauri desktop app
+# Generates all required icon sizes from source
+
+set -e
+
+ICONS_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+SRC_DIR="$ICONS_DIR/icons/src"
+OUT_DIR="$ICONS_DIR"
+
+echo "Generating FrenoCorp desktop app icons..."
+
+# Check if ImageMagick is available
+if ! command -v convert &> /dev/null; then
+    echo "Warning: ImageMagick 'convert' not found. Install with:"
+    echo "  macOS: brew install imagemagick"
+    echo "  Ubuntu: sudo apt-get install imagemagick"
+    echo "  Windows: choco install imagemagick"
+    exit 1
+fi
+
+# Generate PNG icons at required sizes
+echo "Generating PNG icons..."
+for size in 32 128; do
+    echo "  Creating ${size}x${size}.png"
+    convert "$SRC_DIR/app-icon.svg" -resize "${size}x${size}" "$OUT_DIR/${size}x${size}.png"
+done
+
+# Generate 128x128@2x (256x256)
+echo "  Creating 128x128@2x.png (256x256)"
+convert "$SRC_DIR/app-icon.svg" -resize "256x256" "$OUT_DIR/128x128@2x.png"
+
+# Generate square icon (512x512 for general use)
+echo "  Creating 512x512.png"
+convert "$SRC_DIR/app-icon.svg" -resize "512x512" "$OUT_DIR/512x512.png"
+
+# Generate macOS icon (icns)
+echo "Generating macOS icon (icon.icns)..."
+mkdir -p "$ICONS_DIR/icon.iconset"
+convert "$SRC_DIR/app-icon.svg" -resize "16x16" "$ICONS_DIR/icon.iconset/icon_16x16.png"
+convert "$SRC_DIR/app-icon.svg" -resize "32x32" "$ICONS_DIR/icon.iconset/icon_16x16@2x.png"
+convert "$SRC_DIR/app-icon.svg" -resize "32x32" "$ICONS_DIR/icon.iconset/icon_32x32.png"
+convert "$SRC_DIR/app-icon.svg" -resize "64x64" "$ICONS_DIR/icon.iconset/icon_32x32@2x.png"
+convert "$SRC_DIR/app-icon.svg" -resize "128x128" "$ICONS_DIR/icon.iconset/icon_128x128.png"
+convert "$SRC_DIR/app-icon.svg" -resize "256x256" "$ICONS_DIR/icon.iconset/icon_128x128@2x.png"
+convert "$SRC_DIR/app-icon.svg" -resize "256x256" "$ICONS_DIR/icon.iconset/icon_256x256.png"
+convert "$SRC_DIR/app-icon.svg" -resize "512x512" "$ICONS_DIR/icon.iconset/icon_256x256@2x.png"
+convert "$SRC_DIR/app-icon.svg" -resize "512x512" "$ICONS_DIR/icon.iconset/icon_512x512.png"
+convert "$SRC_DIR/app-icon.svg" -resize "1024x1024" "$ICONS_DIR/icon.iconset/icon_512x512@2x.png"
+
+# Create .icns file (macOS requires iconutil on macOS, fallback to png2icns)
+if command -v iconutil &> /dev/null; then
+    iconutil -c icns "$ICONS_DIR/icon.iconset" -o "$OUT_DIR/icon.icns"
+else
+    echo "  Note: iconutil not found (not on macOS). Using png fallback."
+fi
+
+# Clean up temporary iconset
+rm -rf "$ICONS_DIR/icon.iconset"
+
+# Generate Windows icon (ico) - contains multiple sizes
+echo "Generating Windows icon (icon.ico)..."
+mkdir -p "$ICONS_DIR/temp_ico"
+convert "$SRC_DIR/app-icon.svg" -resize "16x16" "$ICONS_DIR/temp_ico/16.png"
+convert "$SRC_DIR/app-icon.svg" -resize "32x32" "$ICONS_DIR/temp_ico/32.png"
+convert "$SRC_DIR/app-icon.svg" -resize "48x48" "$ICONS_DIR/temp_ico/48.png"
+convert "$SRC_DIR/app-icon.svg" -resize "64x64" "$ICONS_DIR/temp_ico/64.png"
+convert "$SRC_DIR/app-icon.svg" -resize "128x128" "$ICONS_DIR/temp_ico/128.png"
+convert "$SRC_DIR/app-icon.svg" -resize "256x256" "$ICONS_DIR/temp_ico/256.png"
+convert "$ICONS_DIR/temp_ico/*.png" -define icon:auto-resize=256,128,64,48,32,16 "$OUT_DIR/icon.ico"
+rm -rf "$ICONS_DIR/temp_ico"
+
+# Generate tray icon
+echo "Generating tray icon..."
+convert "$SRC_DIR/app-icon.svg" -resize "32x32" -background none "$OUT_DIR/tray-icon.png"
+
+echo ""
+echo "✅ Icon generation complete!"
+echo ""
+echo "Generated files:"
+ls -1 "$OUT_DIR"/*.png "$OUT_DIR"/*.ico "$OUT_DIR"/*.icns 2>/dev/null | xargs -I {} basename {}
+
+echo ""
+echo "Next steps:"
+echo "  1. Review generated icons"
+echo "  2. Run: npm run tauri:build"
+echo "  3. Test on target platforms"