fix(dashboard): stop MissionManager rendering mobile+desktop title together

The header rendered both a "Missions" desktop span AND a mobile span
containing the selected mission title simultaneously, relying on CSS to
hide the inactive variant. jsdom doesn't apply media queries, so
testing-library's getByText found the mission title in both the body
cards and the otherwise-hidden mobile header — failing 49 tests with
"Found multiple elements with the text: <title>". Render only the
active variant based on isMobile.

Also clear localStorage in beforeEach so the SWR mission cache from
prior tests doesn't pre-hydrate into the next render and surface its
own fixtures as duplicates.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/dashboard/app/components/MissionManager.tsx

@@ -4205,10 +4205,13 @@ export function MissionManager({ isOpen, isInline = false, onClose, addToast, pr
           )}
           <Target size={18} className="mission-manager__header-icon" />
           <h2 className="mission-manager__title" data-testid="mission-header-title">
-            <span className="mission-manager__title-text mission-manager__title-text--desktop">Missions</span>
-            <span className="mission-manager__title-text mission-manager__title-text--mobile">
-              {selectedMission ? selectedMission.title : "Missions"}
-            </span>
+            {isMobile ? (
+              <span className="mission-manager__title-text mission-manager__title-text--mobile">
+                {selectedMission ? selectedMission.title : "Missions"}
+              </span>
+            ) : (
+              <span className="mission-manager__title-text mission-manager__title-text--desktop">Missions</span>
+            )}
           </h2>
         </div>
         {!isInline && (

packages/dashboard/app/components/__tests__/MissionManager.test.tsx

@@ -740,6 +740,9 @@ describe("MissionManager", () => {
 
   beforeEach(() => {
     mockViewport("desktop");
+    // Reset SWR cache so prior tests' mission lists don't pre-hydrate into the
+    // current render and surface duplicates of fixture titles.
+    localStorage.clear();
     originalFetch = globalThis.fetch;
     originalEventSource = globalThis.EventSource;
     mockFetchAiSession.mockReset();