feat: add mass edit feature for backlog kanban cards

Add ability to select multiple backlog features and edit their configuration
in bulk. Selection is limited to backlog column features in the current
branch/worktree only.

Changes:
- Add selection mode toggle in board controls
- Add checkbox selection on kanban cards (backlog only)
- Disable drag and drop during selection mode
- Hide action buttons during selection mode
- Add floating selection action bar with Edit/Clear/Select All
- Add mass edit dialog with all configuration options in single scroll view
- Add server endpoint for bulk feature updates

apps/ui/src/components/views/board-view.tsx

@@ -56,7 +56,10 @@ import {
   useBoardBackground,
   useBoardPersistence,
   useFollowUpState,
+  useSelectionMode,
 } from './board-view/hooks';
+import { SelectionActionBar } from './board-view/components';
+import { MassEditDialog } from './board-view/dialogs';
 
 // Stable empty array to avoid infinite loop in selector
 const EMPTY_WORKTREES: ReturnType<ReturnType<typeof useAppStore.getState>['getWorktrees']> = [];
@@ -154,6 +157,19 @@ export function BoardView() {
     handleFollowUpDialogChange,
   } = useFollowUpState();
 
+  // Selection mode hook for mass editing
+  const {
+    isSelectionMode,
+    selectedFeatureIds,
+    selectedCount,
+    toggleSelectionMode,
+    toggleFeatureSelection,
+    selectAll,
+    clearSelection,
+    exitSelectionMode,
+  } = useSelectionMode();
+  const [showMassEditDialog, setShowMassEditDialog] = useState(false);
+
   // Search filter for Kanban cards
   const [searchQuery, setSearchQuery] = useState('');
   // Plan approval loading state
@@ -447,6 +463,72 @@ export function BoardView() {
     currentWorktreeBranch,
   });
 
+  // Handler for bulk updating multiple features
+  const handleBulkUpdate = useCallback(
+    async (updates: Partial<Feature>) => {
+      if (!currentProject || selectedFeatureIds.size === 0) return;
+
+      try {
+        const api = getHttpApiClient();
+        const featureIds = Array.from(selectedFeatureIds);
+        const result = await api.features.bulkUpdate(currentProject.path, featureIds, updates);
+
+        if (result.success) {
+          // Update local state
+          featureIds.forEach((featureId) => {
+            updateFeature(featureId, updates);
+          });
+          toast.success(`Updated ${result.updatedCount} features`);
+          exitSelectionMode();
+        } else {
+          toast.error('Failed to update some features', {
+            description: `${result.failedCount} features failed to update`,
+          });
+        }
+      } catch (error) {
+        logger.error('Bulk update failed:', error);
+        toast.error('Failed to update features');
+      }
+    },
+    [currentProject, selectedFeatureIds, updateFeature, exitSelectionMode]
+  );
+
+  // Get selected features for mass edit dialog
+  const selectedFeatures = useMemo(() => {
+    return hookFeatures.filter((f) => selectedFeatureIds.has(f.id));
+  }, [hookFeatures, selectedFeatureIds]);
+
+  // Get backlog feature IDs in current branch for "Select All"
+  const allSelectableFeatureIds = useMemo(() => {
+    return hookFeatures
+      .filter((f) => {
+        // Only backlog features
+        if (f.status !== 'backlog') return false;
+
+        // Filter by current worktree branch
+        const featureBranch = f.branchName;
+        if (!featureBranch) {
+          // No branch assigned - only selectable on primary worktree
+          return currentWorktreePath === null;
+        }
+        if (currentWorktreeBranch === null) {
+          // Viewing main but branch hasn't been initialized
+          return currentProject?.path
+            ? isPrimaryWorktreeBranch(currentProject.path, featureBranch)
+            : false;
+        }
+        // Match by branch name
+        return featureBranch === currentWorktreeBranch;
+      })
+      .map((f) => f.id);
+  }, [
+    hookFeatures,
+    currentWorktreePath,
+    currentWorktreeBranch,
+    currentProject?.path,
+    isPrimaryWorktreeBranch,
+  ]);
+
   // Handler for addressing PR comments - creates a feature and starts it automatically
   const handleAddressPRComments = useCallback(
     async (worktree: WorktreeInfo, prInfo: PRInfo) => {
@@ -1069,6 +1151,8 @@ export function BoardView() {
             onDetailLevelChange={setKanbanCardDetailLevel}
             boardViewMode={boardViewMode}
             onBoardViewModeChange={setBoardViewMode}
+            isSelectionMode={isSelectionMode}
+            onToggleSelectionMode={toggleSelectionMode}
           />
         </div>
         {/* View Content - Kanban or Graph */}
@@ -1109,6 +1193,9 @@ export function BoardView() {
               currentProject?.path ? pipelineConfigByProject[currentProject.path] || null : null
             }
             onOpenPipelineSettings={() => setShowPipelineSettings(true)}
+            isSelectionMode={isSelectionMode}
+            selectedFeatureIds={selectedFeatureIds}
+            onToggleFeatureSelection={toggleFeatureSelection}
           />
         ) : (
           <GraphView
@@ -1134,6 +1221,27 @@ export function BoardView() {
         )}
       </div>
 
+      {/* Selection Action Bar */}
+      {isSelectionMode && (
+        <SelectionActionBar
+          selectedCount={selectedCount}
+          totalCount={allSelectableFeatureIds.length}
+          onEdit={() => setShowMassEditDialog(true)}
+          onClear={clearSelection}
+          onSelectAll={() => selectAll(allSelectableFeatureIds)}
+        />
+      )}
+
+      {/* Mass Edit Dialog */}
+      <MassEditDialog
+        open={showMassEditDialog}
+        onClose={() => setShowMassEditDialog(false)}
+        selectedFeatures={selectedFeatures}
+        onApply={handleBulkUpdate}
+        showProfilesOnly={showProfilesOnly}
+        aiProfiles={aiProfiles}
+      />
+
       {/* Board Background Modal */}
       <BoardBackgroundModal
         open={showBoardBackgroundModal}