feat: add feature editing capability for pending/in-progress features

Add the ability for users to edit features that are not yet completed,
allowing them to provide corrections or additional instructions when the
agent is stuck or implementing a feature incorrectly.

Backend changes:
- Add FeatureUpdate schema in server/schemas.py with optional fields
- Add PATCH /api/projects/{project_name}/features/{feature_id} endpoint
- Validate that completed features (passes=True) cannot be edited

Frontend changes:
- Add FeatureUpdate type in ui/src/lib/types.ts
- Add updateFeature() API function in ui/src/lib/api.ts
- Add useUpdateFeature() React Query mutation hook
- Create EditFeatureForm.tsx component with pre-filled form values
- Update FeatureModal.tsx with Edit button for non-completed features

The edit form allows modifying category, name, description, priority,
and test steps. Save button is disabled until changes are detected.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ui/src/components/FeatureModal.tsx

@@ -1,6 +1,7 @@
 import { useState } from 'react'
-import { X, CheckCircle2, Circle, SkipForward, Trash2, Loader2, AlertCircle } from 'lucide-react'
+import { X, CheckCircle2, Circle, SkipForward, Trash2, Loader2, AlertCircle, Pencil } from 'lucide-react'
 import { useSkipFeature, useDeleteFeature } from '../hooks/useProjects'
+import { EditFeatureForm } from './EditFeatureForm'
 import type { Feature } from '../lib/types'
 
 interface FeatureModalProps {
@@ -12,6 +13,7 @@ interface FeatureModalProps {
 export function FeatureModal({ feature, projectName, onClose }: FeatureModalProps) {
   const [error, setError] = useState<string | null>(null)
   const [showDeleteConfirm, setShowDeleteConfirm] = useState(false)
+  const [showEdit, setShowEdit] = useState(false)
 
   const skipFeature = useSkipFeature(projectName)
   const deleteFeature = useDeleteFeature(projectName)
@@ -36,6 +38,18 @@ export function FeatureModal({ feature, projectName, onClose }: FeatureModalProp
     }
   }
 
+  // Show edit form when in edit mode
+  if (showEdit) {
+    return (
+      <EditFeatureForm
+        feature={feature}
+        projectName={projectName}
+        onClose={() => setShowEdit(false)}
+        onSaved={onClose}
+      />
+    )
+  }
+
   return (
     <div className="neo-modal-backdrop" onClick={onClose}>
       <div
@@ -159,6 +173,14 @@ export function FeatureModal({ feature, projectName, onClose }: FeatureModalProp
               </div>
             ) : (
               <div className="flex gap-3">
+                <button
+                  onClick={() => setShowEdit(true)}
+                  disabled={skipFeature.isPending}
+                  className="neo-btn neo-btn-primary flex-1"
+                >
+                  <Pencil size={18} />
+                  Edit
+                </button>
                 <button
                   onClick={handleSkip}
                   disabled={skipFeature.isPending}
@@ -169,7 +191,7 @@ export function FeatureModal({ feature, projectName, onClose }: FeatureModalProp
                   ) : (
                     <>
                       <SkipForward size={18} />
-                      Skip (Move to End)
+                      Skip
                     </>
                   )}
                 </button>