Add delete confirmation dialog for kanban cards

When clicking the trash icon to delete a feature card, users now see a
confirmation dialog asking them to confirm the deletion. This prevents
accidental deletions and provides a clear cancel option.

- Added Dialog component with confirm/cancel buttons to kanban-card
- Updated mock electron API to support test feature injection via __mockFeatures
- Added test utilities for delete confirmation dialog interactions
- Fixed test infrastructure to properly load mock features

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/src/store/app-store.ts

@@ -52,6 +52,7 @@ export interface Feature {
   status: "backlog" | "in_progress" | "verified";
   images?: FeatureImage[];
   startedAt?: string; // ISO timestamp for when the card moved to in_progress
+  skipTests?: boolean; // When true, skip TDD approach and require manual verification
 }
 
 export interface AppState {