fix: remove mobile composer annotation line

scripts/test-mobile-create-ui-policy.mjs

@@ -75,6 +75,8 @@ await runTest('mobile conversation is separated from the bottom composer instead
   assert.match(css, /\.create-chat-thread\s*\{[^}]*overflow-y:\s*auto/, 'mobile conversation thread should scroll independently above the composer');
   assert.match(css, /\.create-mobile-dialog-composer\s*\{[^}]*position:\s*sticky/, 'mobile composer should stay in layout flow instead of overlaying the conversation');
   assert.doesNotMatch(css, /\.create-mobile-dialog-composer\s*\{[^}]*position:\s*fixed/, 'mobile composer must not be fixed because it covers prompts and previews');
+  assert.doesNotMatch(css, /\.create-mobile-dialog-composer::before/, 'mobile composer should not render the user screenshot annotation as a red divider');
+  assert.doesNotMatch(css, /rgb\(219 73 50/, 'mobile create UI should not include a hard-coded red annotation line');
 });
 
 if (process.exitCode) process.exit(process.exitCode);

src/app/globals.css

@@ -829,18 +829,6 @@
       -webkit-backdrop-filter: blur(24px) saturate(130%);
     }
 
-    .create-mobile-dialog-composer::before {
-      content: "";
-      position: sticky;
-      top: 0;
-      z-index: 2;
-      display: block;
-      height: 3px;
-      margin: -0.75rem -0.75rem 0.72rem;
-      border-radius: 999px;
-      background: rgb(219 73 50 / 0.92);
-    }
-
     .create-mobile-dialog-composer:empty {
       display: none;
     }