site: owner-only dashboard link in header, mobile menu and homepage (g then d from any page); /start skips the site chrome JS

- Header/footer moved to #lib/components/SiteChrome.svelte, returned by a universal
  +layout.ts load only for non-immersive pages, so /start and the book reader never
  download icon libraries, dropdowns or the bits-ui Sheet. /start: 36 -> 18 JS files,
  133 -> 78 KB gzip.
- Header logo is a hashed asset (inlined), so it is cached with the build.
- inlineStyleThreshold 4096: tiny page/component CSS is inlined into the HTML.
- Umami is not loaded on /start.

vite.config.ts

@@ -20,6 +20,10 @@ export default defineConfig({
 			// https, which is right for both staging and production from one image.
 			adapter: adapter(),
 
+			// Inline tiny stylesheets (component/page CSS) into the HTML: one request fewer per
+			// page. The big shared app.css stays a cached /_app/immutable file.
+			inlineStyleThreshold: 4096,
+
 			csrf: {
 				// Allow form posts from the dev site, which Caddy also serves over https.
 				trustedOrigins: ['https://dev.stanrunge.dev']