feat(ext/shared): add Device + FieldHistory types + 8 new message types

Device: name, public_key (hex), added_at.
FieldHistoryView: field_id, field_name, current_value, entries[].
Messages: list_devices, add_device, revoke_device, list_trashed,
restore_item, purge_item, purge_all_trash, get_field_history.

Also adds stub cases in popup-only.ts switch to keep tsc happy until
Tasks 3-5 wire up the real handlers.

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

extension/src/service-worker/router/popup-only.ts

@@ -290,6 +290,17 @@ export async function handle(
         return { ok: false, error: 'download_failed' };
       }
     }
+
+    // Handlers for these cases are added in Tasks 3–5.
+    case 'list_devices':
+    case 'add_device':
+    case 'revoke_device':
+    case 'list_trashed':
+    case 'restore_item':
+    case 'purge_item':
+    case 'purge_all_trash':
+    case 'get_field_history':
+      return { ok: false, error: 'not_implemented' };
   }
 }