feat(FN-970): add mission badge to TaskCard with navigation to MissionManager

- Add mission badge UI to TaskCard showing linked mission name with colored indicator
- Wire up onOpenMission prop through App → Board → Column → WorktreeGroup → TaskCard
- Add CSS styles for mission badge with hover and click states
- Update MissionManager with openMission callback support for navigation from cards
- Add comprehensive tests for mission badge rendering, click behavior, and edge cases

packages/dashboard/app/components/Board.tsx

@@ -42,6 +42,8 @@ interface BoardProps {
   onToggleModelFavorite?: (modelId: string) => void;
   /** Project-level stuck task timeout in milliseconds (undefined = disabled) */
   taskStuckTimeoutMs?: number;
+  /** Called when user clicks a mission badge on a task card */
+  onOpenMission?: (missionId: string) => void;
 }
 
 function sortTasksForColumn(tasks: Task[]): Task[] {
@@ -60,7 +62,7 @@ function areTaskArraysEqual(previous: Task[], next: Task[]): boolean {
   return previous.every((task, index) => task === next[index]);
 }
 
-export function Board({ tasks, projectId, maxConcurrent, onMoveTask, onOpenDetail, addToast, onQuickCreate, onNewTask, autoMerge, onToggleAutoMerge, globalPaused, onUpdateTask, onArchiveTask, onUnarchiveTask, onArchiveAllDone, searchQuery = "", availableModels, onPlanningMode, onSubtaskBreakdown, onOpenDetailWithTab, favoriteProviders, favoriteModels, onToggleFavorite, onToggleModelFavorite, taskStuckTimeoutMs }: BoardProps) {
+export function Board({ tasks, projectId, maxConcurrent, onMoveTask, onOpenDetail, addToast, onQuickCreate, onNewTask, autoMerge, onToggleAutoMerge, globalPaused, onUpdateTask, onArchiveTask, onUnarchiveTask, onArchiveAllDone, searchQuery = "", availableModels, onPlanningMode, onSubtaskBreakdown, onOpenDetailWithTab, favoriteProviders, favoriteModels, onToggleFavorite, onToggleModelFavorite, taskStuckTimeoutMs, onOpenMission }: BoardProps) {
   const [archivedCollapsed, setArchivedCollapsed] = useState(true);
   const { fetchBatch } = useBatchBadgeFetch(projectId);
   const debounceTimeoutRef = useRef<ReturnType<typeof setTimeout> | null>(null);
@@ -178,6 +180,7 @@ export function Board({ tasks, projectId, maxConcurrent, onMoveTask, onOpenDetai
             onToggleModelFavorite={onToggleModelFavorite}
             isSearchActive={isSearchActive}
             taskStuckTimeoutMs={taskStuckTimeoutMs}
+            onOpenMission={onOpenMission}
             {...(col === "triage" ? { onQuickCreate, onNewTask, onPlanningMode, onSubtaskBreakdown } : {})}
             {...(col === "in-review" ? { autoMerge, onToggleAutoMerge } : {})}
             {...(col === "done" ? { onArchiveAllDone } : {})}