feat(assets): standardize asset configuration with capacitor-assets

- Replace manual ImageMagick scripts with official capacitor-assets toolchain
- Consolidate duplicate asset sources to single resources/ directory
- Implement comprehensive asset configuration schema and validation
- Add CI safeguards for asset validation and platform asset detection
- Convert capacitor.config.json to TypeScript format
- Pin Node.js version for deterministic builds
- Remove legacy manual asset generation scripts:
  * generate-icons.sh, generate-ios-assets.sh, generate-android-icons.sh
  * check-android-resources.sh, check-ios-resources.sh
  * purge-generated-assets.sh
- Add new asset management commands:
  * assets:config - generate/update configurations
  * assets:validate - validate configurations
  * assets:clean - clean generated assets (dev only)
  * build:native - build with asset generation
- Create GitHub Actions workflow for asset validation
- Update documentation with new asset management workflow

This standardization eliminates asset duplication, improves build reliability,
and provides a maintainable asset management system using Capacitor defaults.

Breaking Changes: Manual asset generation scripts removed
Migration: Assets now sourced from resources/ directory only
CI: Automated validation prevents committed platform assets

README.md

@@ -136,11 +136,50 @@ const apiUrl = `${APP_SERVER}/api/claim/123`;
 
 See [TESTING.md](test-playwright/TESTING.md) for detailed test instructions.
 
-## Icons
+## Asset Management
 
-Application icons are in the `assets` directory, processed by the `capacitor-assets` command.
+TimeSafari uses a standardized asset configuration system for consistent
+icon and splash screen generation across all platforms.
 
-To add a Font Awesome icon, add to fontawesome.ts and reference with `font-awesome` element and `icon` attribute with the hyphenated name.
+### Asset Sources
+
+- **Single source of truth**: `resources/` directory (Capacitor default)
+- **Source files**: `icon.png`, `splash.png`, `splash_dark.png`
+- **Format**: PNG or SVG files for optimal quality
+
+### Asset Generation
+
+- **Configuration**: `config/assets/capacitor-assets.config.json`
+- **Schema validation**: `config/assets/schema.json`
+- **Build-time generation**: Platform assets generated via `capacitor-assets`
+- **No VCS commits**: Generated assets are never committed to version control
+
+### Development Commands
+
+```bash
+# Generate/update asset configurations
+npm run assets:config
+
+# Validate asset configurations
+npm run assets:validate
+
+# Clean generated platform assets (local dev only)
+npm run assets:clean
+
+# Build with asset generation
+npm run build:native
+```
+
+### Platform Support
+
+- **Android**: Adaptive icons with foreground/background, monochrome support
+- **iOS**: LaunchScreen storyboard preferred, splash assets when needed
+- **Web**: PWA icons generated during build to `dist/` (not committed)
+
+### Font Awesome Icons
+
+To add a Font Awesome icon, add to `fontawesome.ts` and reference with
+`font-awesome` element and `icon` attribute with the hyphenated name.
 
 ## Other