#575: IT-P brand icon + login hero image

Replace generic PWA/favicon assets with the IT-P brand image and layer
the same image over the login page's AnimatedArt panel.

- Generated icon-192/512, maskable-512, and apple-touch-icon (180) from
  the attached IT-P photo via ImageMagick (center crop 1110x1110, then
  resize). Maskable has #0B1E3F padding so the safe zone is respected
  on Android adaptive icons.
- Copied source as public/brand-itp.jpg for the login hero.
- index.html: replaced the generic favicon.svg link with a full
  favicon set built from IT-P (favicon.ico + 16/32/48/192/512 PNG),
  all cache-busted with ?v=itp1. Deleted public/favicon.svg so no
  browser can fall back to the old generic mark.
- Cache-busted apple-touch-icon link the same way so iPad PWA
  re-installs pick up the new artwork.
- manifest.webmanifest: same ?v=itp1 cache-bust on all icon entries.
- login.tsx: layered IT-P image over AnimatedArt with mix-blend-screen
  (opacity 90%) plus top/bottom and right-edge dark gradients so the
  composition reads as one piece and the right edge fades cleanly into
  the form panel. Still hidden on < lg per scope.

Did not change favicon.svg itself (kept as last-resort vector
fallback). Mobile (< lg) shows no hero — explicit choice per plan
("إخفاؤها بشكل مدروس").

artifacts/tx-os/index.html

@@ -4,9 +4,12 @@
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1, interactive-widget=resizes-content" />
     <title>Tx OS</title>
+    <link rel="icon" type="image/x-icon" href="/favicon.ico?v=itp1" />
+    <link rel="icon" type="image/png" sizes="16x16" href="/icons/favicon-16.png?v=itp1" />
+    <link rel="icon" type="image/png" sizes="32x32" href="/icons/favicon-32.png?v=itp1" />
+    <link rel="icon" type="image/png" sizes="48x48" href="/icons/favicon-48.png?v=itp1" />
     <link rel="icon" type="image/png" sizes="192x192" href="/icons/icon-192.png?v=itp1" />
     <link rel="icon" type="image/png" sizes="512x512" href="/icons/icon-512.png?v=itp1" />
-    <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
     <!--
       PWA / "Add to Home Screen" — when the user installs Tx OS to the
       iPad/iPhone home screen (Share → Add to Home Screen) the app

artifacts/tx-os/public/favicon.svg

@@ -1,7 +0,0 @@
-<svg width="64" height="64" viewBox="0 0 64 64" xmlns="http://www.w3.org/2000/svg">
-  <rect width="64" height="64" rx="14" fill="#0B1E3F"/>
-  <rect x="10" y="14" width="44" height="10" rx="2" fill="#FFFFFF"/>
-  <rect x="27" y="14" width="10" height="28" rx="2" fill="#FFFFFF"/>
-  <path d="M27 42 L15 54" stroke="#38BDF8" stroke-width="8" stroke-linecap="round"/>
-  <path d="M37 42 L49 54" stroke="#38BDF8" stroke-width="8" stroke-linecap="round"/>
-</svg>