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

scripts/assets-config.js

@@ -0,0 +1,174 @@
+#!/usr/bin/env node
+
+/**
+ * TimeSafari Asset Configuration Generator
+ * Generates capacitor-assets configuration files with deterministic outputs
+ * Author: Matthew Raymer
+ * 
+ * Usage: node scripts/assets-config.js
+ */
+
+import fs from 'fs';
+import path from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+const PROJECT_ROOT = path.dirname(__dirname);
+
+/**
+ * Generate deterministic capacitor-assets configuration
+ * @returns {Object} Sorted, stable configuration object
+ */
+function generateAssetConfig() {
+  const config = {
+    icon: {
+      source: "resources/icon.png",
+      android: {
+        adaptive: {
+          foreground: "resources/icon.png",
+          background: "#121212",
+          monochrome: "resources/icon.png"
+        },
+        target: "android/app/src/main/res"
+      },
+      ios: {
+        padding: 0,
+        target: "ios/App/App/Assets.xcassets/AppIcon.appiconset"
+      },
+      web: {
+        target: "public/img/icons"
+      }
+    },
+    splash: {
+      source: "resources/splash.png",
+      darkSource: "resources/splash_dark.png",
+      android: {
+        scale: "cover",
+        target: "android/app/src/main/res"
+      },
+      ios: {
+        useStoryBoard: true,
+        target: "ios/App/App/Assets.xcassets"
+      }
+    }
+  };
+
+  return sortObjectKeys(config);
+}
+
+/**
+ * Sort object keys recursively for deterministic output
+ * @param {Object} obj - Object to sort
+ * @returns {Object} Object with sorted keys
+ */
+function sortObjectKeys(obj) {
+  if (obj === null || typeof obj !== 'object') {
+    return obj;
+  }
+
+  if (Array.isArray(obj)) {
+    return obj.map(sortObjectKeys);
+  }
+
+  const sorted = {};
+  Object.keys(obj)
+    .sort()
+    .forEach(key => {
+      sorted[key] = sortObjectKeys(obj[key]);
+    });
+
+  return sorted;
+}
+
+/**
+ * Validate that required source files exist
+ */
+function validateSourceFiles() {
+  const requiredFiles = [
+    'resources/icon.png',
+    'resources/splash.png',
+    'resources/splash_dark.png'
+  ];
+
+  const missingFiles = requiredFiles.filter(file => {
+    const filePath = path.join(PROJECT_ROOT, file);
+    return !fs.existsSync(filePath);
+  });
+
+  if (missingFiles.length > 0) {
+    console.error('❌ Missing required source files:');
+    missingFiles.forEach(file => console.error(`   ${file}`));
+    process.exit(1);
+  }
+
+  console.log('✅ All required source files found');
+}
+
+/**
+ * Write configuration to file with consistent formatting
+ * @param {Object} config - Configuration object
+ * @param {string} outputPath - Output file path
+ */
+function writeConfig(config, outputPath) {
+  const jsonString = JSON.stringify(config, null, 2);
+  
+  // Ensure consistent line endings and no trailing whitespace
+  const cleanJson = jsonString
+    .split('\n')
+    .map(line => line.trimEnd())
+    .join('\n') + '\n';
+
+  fs.writeFileSync(outputPath, cleanJson, 'utf8');
+  console.log(`✅ Configuration written to: ${outputPath}`);
+}
+
+/**
+ * Main execution function
+ */
+function main() {
+  console.log('🔄 Generating TimeSafari asset configuration...');
+  console.log(`📁 Project root: ${PROJECT_ROOT}`);
+  console.log(`📅 Generated: ${new Date().toISOString()}`);
+
+  try {
+    // Validate source files exist
+    validateSourceFiles();
+
+    // Generate configuration
+    const config = generateAssetConfig();
+
+    // Ensure config directory exists
+    const configDir = path.join(PROJECT_ROOT, 'config', 'assets');
+    if (!fs.existsSync(configDir)) {
+      fs.mkdirSync(configDir, { recursive: true });
+    }
+
+    // Write configuration files
+    const capacitorAssetsConfigPath = path.join(configDir, 'capacitor-assets.config.json');
+    writeConfig(config, capacitorAssetsConfigPath);
+
+    // Copy to root for capacitor-assets discovery
+    const rootConfigPath = path.join(PROJECT_ROOT, 'capacitor-assets.config.json');
+    writeConfig(config, rootConfigPath);
+
+    console.log('🎉 Asset configuration generation completed successfully!');
+    console.log('');
+    console.log('📋 Next steps:');
+    console.log('   1. Review the generated configuration');
+    console.log('   2. Commit the configuration files');
+    console.log('   3. Run "npm run assets:validate" to verify');
+    console.log('   4. Use "npm run build:native" for builds');
+
+  } catch (error) {
+    console.error('❌ Configuration generation failed:', error.message);
+    process.exit(1);
+  }
+}
+
+// Run if called directly
+if (import.meta.url === `file://${process.argv[1]}`) {
+  main();
+}
+
+export { generateAssetConfig, sortObjectKeys, validateSourceFiles };