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/server/src/routes/features/index.ts

@@ -9,6 +9,7 @@ import { createListHandler } from './routes/list.js';
 import { createGetHandler } from './routes/get.js';
 import { createCreateHandler } from './routes/create.js';
 import { createUpdateHandler } from './routes/update.js';
+import { createBulkUpdateHandler } from './routes/bulk-update.js';
 import { createDeleteHandler } from './routes/delete.js';
 import { createAgentOutputHandler, createRawOutputHandler } from './routes/agent-output.js';
 import { createGenerateTitleHandler } from './routes/generate-title.js';
@@ -20,6 +21,11 @@ export function createFeaturesRoutes(featureLoader: FeatureLoader): Router {
   router.post('/get', validatePathParams('projectPath'), createGetHandler(featureLoader));
   router.post('/create', validatePathParams('projectPath'), createCreateHandler(featureLoader));
   router.post('/update', validatePathParams('projectPath'), createUpdateHandler(featureLoader));
+  router.post(
+    '/bulk-update',
+    validatePathParams('projectPath'),
+    createBulkUpdateHandler(featureLoader)
+  );
   router.post('/delete', validatePathParams('projectPath'), createDeleteHandler(featureLoader));
   router.post('/agent-output', createAgentOutputHandler(featureLoader));
   router.post('/raw-output', createRawOutputHandler(featureLoader));

apps/server/src/routes/features/routes/bulk-update.ts

@@ -0,0 +1,75 @@
+/**
+ * POST /bulk-update endpoint - Update multiple features at once
+ */
+
+import type { Request, Response } from 'express';
+import { FeatureLoader } from '../../../services/feature-loader.js';
+import type { Feature } from '@automaker/types';
+import { getErrorMessage, logError } from '../common.js';
+
+interface BulkUpdateRequest {
+  projectPath: string;
+  featureIds: string[];
+  updates: Partial<Feature>;
+}
+
+interface BulkUpdateResult {
+  featureId: string;
+  success: boolean;
+  error?: string;
+}
+
+export function createBulkUpdateHandler(featureLoader: FeatureLoader) {
+  return async (req: Request, res: Response): Promise<void> => {
+    try {
+      const { projectPath, featureIds, updates } = req.body as BulkUpdateRequest;
+
+      if (!projectPath || !featureIds || !Array.isArray(featureIds) || featureIds.length === 0) {
+        res.status(400).json({
+          success: false,
+          error: 'projectPath and featureIds (non-empty array) are required',
+        });
+        return;
+      }
+
+      if (!updates || Object.keys(updates).length === 0) {
+        res.status(400).json({
+          success: false,
+          error: 'updates object with at least one field is required',
+        });
+        return;
+      }
+
+      const results: BulkUpdateResult[] = [];
+      const updatedFeatures: Feature[] = [];
+
+      for (const featureId of featureIds) {
+        try {
+          const updated = await featureLoader.update(projectPath, featureId, updates);
+          results.push({ featureId, success: true });
+          updatedFeatures.push(updated);
+        } catch (error) {
+          results.push({
+            featureId,
+            success: false,
+            error: getErrorMessage(error),
+          });
+        }
+      }
+
+      const successCount = results.filter((r) => r.success).length;
+      const failureCount = results.filter((r) => !r.success).length;
+
+      res.json({
+        success: failureCount === 0,
+        updatedCount: successCount,
+        failedCount: failureCount,
+        results,
+        features: updatedFeatures,
+      });
+    } catch (error) {
+      logError(error, 'Bulk update features failed');
+      res.status(500).json({ success: false, error: getErrorMessage(error) });
+    }
+  };
+}