FN-5647: remove errant right border on mobile regular chat composer

Fusion-Task-Id: FN-5647

Fusion-Task-Lineage: 278367a7-a3bb-4591-b117-06d17ee71241

packages/dashboard/app/components/ChatView.css

@@ -1419,6 +1419,8 @@
   flex: 0 0 auto;
   width: 100%;
   box-sizing: border-box;
+  -webkit-appearance: none;
+  appearance: none;
   resize: none;
   border: 1px solid var(--border);
   border-radius: 12px;

packages/dashboard/app/components/__tests__/ChatView.regular-composer-no-right-line.test.tsx

@@ -94,6 +94,8 @@ describe("ChatView regular composer right-edge artifact regression", () => {
     expect(textareaRule).not.toBeNull();
     expect(textareaRule?.[0]).toContain("box-sizing: border-box");
     expect(textareaRule?.[0]).toContain("width: 100%");
+    expect(textareaRule?.[0]).toContain("-webkit-appearance: none");
+    expect(textareaRule?.[0]).toContain("appearance: none");
 
     const wrapperRule = chatViewCss.match(/\.chat-input-wrapper\s*\{[^}]*\}/);
     expect(wrapperRule).not.toBeNull();