Restyle the connect and setup pages in the Shelf look

[KodeStar]

The server's own HTML pages still wore the pre-redesign look: violet #7c3aed, Roboto, the "AUDIO"/"SILO" wordmark, dark only. This restyles all of them in the console's Shelf look. ADMIN-CONSOLE-PLAN.md lists this as a Phase 6 item.

Pages restyled. These are the only server-rendered pages outside the console and the player:

• / and /connect, the connect page with the auth code, QR and links.
• /setup, the first-run wizard.
• /admin when the console isn't built (the dev-only 503 page).

What changed

• internal/web/assets/style.css
  • Shelf tokens (light + dark) copied from admin-ui/src/styles/globals.css.
  • Card, field and button rules mirror the console's sign-in page.
  • The brand row is the ink tile + "AudioSilo" wordmark. The mark is favicon.svg used as a CSS mask, so its path isn't duplicated.
• Fonts. Self-hosted Figtree + Bricolage Grotesque variable woff2 (latin, OFL) replace the three Roboto files.
• theme-init.js
  • A copy of the console's own script. It reads the same storage key, so a theme chosen in /admin carries over; with none stored, the pages follow the system theme.
  • It is loaded before the stylesheet.
• Sync tests. shelf_sync_test.go fails if theme-init.js or the copied colour tokens drift from admin-ui.
• Service worker (scope /, so it sees these pages once an admin has opened the console).
  • Unhashed /assets/*.css|js are now network-first, like the console's theme-init.js. A cached old style.css would otherwise render the new markup broken once after the upgrade.
  • VERSION is bumped so cached Roboto files are dropped.
  • Covered by a case in admin-ui/src/test/sw.test.ts.
• Unchanged. Ids, data-i18n* attributes and script tags are the same, so connect.js, setup.js and the i18n engine are untouched. No inline style or script; the strict CSP holds.
• No wire change.

Verified in a real browser (Chromium via Playwright, scratch data dirs)

• Connect page, light and dark: entry state, wrong code (error line), redeem via #code= (fragment stripped; QR, uses note, the three links).
• Language switch: German and Spanish.
• Phone widths: 375 px and 320 px. No horizontal scroll, and the QR stays square.
• Theme carry-over: a theme stored by the console wins over the system preference.
• Setup wizard, light and dark: the form, plus the "all set" state after a real submit.
• "Console not built" page: light and dark.
• Fonts: both load.
• Console errors: none apart from the expected 401 (wrong code) and 503 (not-built page).

Not changed / follow-ups

• favicon.svg, the PWA icons and the manifest still use the old violet mark. Changing the brand icon is a separate decision.
• The pages set the theme at load. Unlike the console, they don't follow an OS light/dark switch while open.

Docs: KodeStar/audiosilo-docs (regenerated server/connect-page.png and server/setup-wizard.png), PR linked below once open.