fix(test): update mobile navbar test for bottom-nav design

The test expected .top-navbar visible on mobile, but the simplified
design hides it and shows .bottom-nav instead.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/tests/qa/test_qa_responsive.py

@@ -89,14 +89,14 @@ def test_responsive_page(
 # ---------------------------------------------------------------------------
 
 def test_mobile_navbar_visible(pw_browser, base_url: str):
-    """Mobile viewport: navbar should still be visible and functional."""
+    """Mobile viewport: bottom nav should be visible (top navbar hidden on mobile)."""
     context = pw_browser.new_context(viewport=VIEWPORTS["mobile"])
     page = context.new_page()
     try:
         page.goto(base_url, wait_until="networkidle", timeout=15_000)
-        # Custom navbar: .top-navbar with .navbar-brand
-        navbar = page.locator(".top-navbar")
-        expect(navbar).to_be_visible()
+        # On mobile, top-navbar is hidden and bottom-nav is shown
+        bottom_nav = page.locator(".bottom-nav")
+        expect(bottom_nav).to_be_visible()
     finally:
         context.close()