feat(pwa): make the app installable

Manifest, gamepad icon (also the new favicon, instead of
the Vite logo), iOS meta tags and the tab title
ToBePlayed. No service worker, so a deploy never meets
an old cached bundle. The title bar color follows
light and dark mode. The README also lists adding a
game by name.

README.md

@@ -26,6 +26,8 @@ To Be Played is split into three repositories:
   priority first, reroll without repeats, and "Start playing" in one click.
 - **Library**: status filters, "short games" filter (up to 10 h), search, sorting by playtime, recently seen, newest
   in library, rating or priority, paging. Each row shows the unlocked achievements.
+- **Add a game by name** for games outside Steam (PlayStation, Switch, Xbox, physical): search IGDB, pick a hit,
+  a platform and optional hours. Works without a Steam ID.
 - **Game detail**: status, priority, 1–5 star rating, notes, achievements, time to beat (story / extras / 100 %),
   a hint when Steam shows recent playtime for a game still in the backlog, and one to set the status to 100 % when
   every achievement is unlocked.
@@ -34,6 +36,7 @@ To Be Played is split into three repositories:
 - **Appearance**: accent color, corner style, wide layout, page background and banner from your own game art.
   Saved in Auth, so it follows you to every device.
 - German and English, dark mode, mobile layout, session-expired message instead of a silent logout.
+- **Installable** as an app on phone and desktop (web app manifest, no service worker, so no offline mode).
 - **Session**: the tokens are HttpOnly cookies that no script can read. `apiFetch` renews an expired access token
   once and sends the request again; parallel requests and other tabs share one refresh.
 
@@ -88,7 +91,6 @@ npm run build
 
 - Mood filter for "What to play next".
 - A Content Security Policy in `nginx.conf`.
-- Installable PWA.
 
 ## License