feat: implement Preview module dialog and improve submit toast feedback

- Added Preview module dialog showing all configured modules with their content
- Preview shows passages, listening sections, writing tasks, speaking parts
- Displays module badges (timer, difficulty, access type)
- Improved submit toast: shows exam ID, status, and duration (8s)
- Preview button now enabled when a module is active
- Added .vite to .gitignore, added .dockerignore

Made-with: Cursor

.dockerignore

@@ -0,0 +1,10 @@
+node_modules
+dist
+.git
+.env
+.env.local
+.env.production
+*.md
+docs/
+.vscode/
+coverage/