feat: add export functionality for web API with demo script

- Add export API endpoint POST /web/v1/accounts/export
- Support two export modes: text (data strings) and object (full account objects)
- Automatically set account status to 'exported' during export
- Add comprehensive demo script that uploads, exports and verifies functionality
- Update API documentation with export endpoint details
- Add TypeScript types for export functionality

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

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

.claude/settings.local.json

@@ -2,7 +2,12 @@
   "permissions": {
     "allow": [
       "Bash(mkdir:*)",
-      "Bash(git init:*)"
+      "Bash(git init:*)",
+      "Bash(git remote:*)",
+      "Bash(git push:*)",
+      "Bash(git add:*)",
+      "Bash(git add:*)",
+      "Bash(git push:*)"
     ],
     "deny": []
   }