Ship PWA app icons and correct the manifest theme color

vite.config.ts

@@ -35,18 +35,25 @@ export default defineConfig({
     react(),
     VitePWA({
       registerType: 'prompt',
-      includeAssets: ['favicon.svg'],
+      includeAssets: ['favicon.svg', 'icon-maskable.svg', 'icon-mono.svg'],
       manifest: {
         name: 'Astrolabe',
         short_name: 'Astrolabe',
         description: 'A browser-based snippet manager for Vega-Lite visualizations.',
-        theme_color: '#1a1a2e',
+        // theme_color tints the OS/browser chrome; background_color is the splash
+        // behind the icon. theme_color is the app accent (`--accent`, light theme);
+        // background_color matches the light `--bg` the app boots into.
+        theme_color: '#0e7490',
         background_color: '#ffffff',
         display: 'standalone',
-        // TODO: theme_color/background_color are stale placeholders — '#1a1a2e' was
-        // the old --color-text hex, retired by the M1.5 token rename. Re-pick from
-        // the settled palette (and reconcile with light/dark) when icons land.
-        icons: [],
+        // SVG marks scale to any size — Chrome/Edge/desktop install accept SVG
+        // icons. (iOS home-screen still prefers a PNG apple-touch-icon; tracked as
+        // a known residual.) maskable = Android adaptive; monochrome = tinted mark.
+        icons: [
+          { src: 'favicon.svg', sizes: 'any', type: 'image/svg+xml', purpose: 'any' },
+          { src: 'icon-maskable.svg', sizes: 'any', type: 'image/svg+xml', purpose: 'maskable' },
+          { src: 'icon-mono.svg', sizes: 'any', type: 'image/svg+xml', purpose: 'monochrome' },
+        ],
       },
       workbox: {
         // Workbox's default globPatterns omit woff2; add it so the self-hosted