feat(17-04): wire favicons + theme-color in index.html, fix maskable icon + accent in manifest

- index.html: add favicon.svg (SVG, modern browsers first) + favicon.ico (legacy) links
- index.html: update theme-color from #4A90D9 to approved #e8915a (warm amber)
- vite.config.ts: fix maskable icon — reference /icon-maskable-512.png (separate file) not /icon-512.png
- vite.config.ts: update manifest theme_color to #e8915a to match index.html
- tokens.css: update --color-member-0 to #e8915a (warm amber, Variant B, operator-approved 17-02)
- --sx-color-primary follows automatically via var(--color-member-0)

apps/pwa/vite.config.ts

@@ -30,7 +30,7 @@ export default defineConfig({
         name: 'FamilySync',
         short_name: 'FamilySync',
         description: 'Family calendar and lists',
-        theme_color: '#4A90D9',
+        theme_color: '#e8915a',
         background_color: '#ffffff',
         display: 'standalone',
         scope: '/',
@@ -38,7 +38,7 @@ export default defineConfig({
         icons: [
           { src: '/icon-192.png', sizes: '192x192', type: 'image/png' },
           { src: '/icon-512.png', sizes: '512x512', type: 'image/png' },
-          { src: '/icon-512.png', sizes: '512x512', type: 'image/png', purpose: 'maskable' },
+          { src: '/icon-maskable-512.png', sizes: '512x512', type: 'image/png', purpose: 'maskable' },
         ],
       },
     }),