refactor(frontend,plugins): normalise les DTOs review backend et corrige le mock (#120)

- plugin.ts: normalizeReview() garantit issues/installable définis même si backend omet ces champs
- mock/index.ts: MockPluginGateway.uninstall() retourne removalOutcome pour cohérence avec le domaine
- domain/index.ts: PluginUninstallResult ajoute removalOutcome optionnel
- Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/adapters/mock/index.ts

@@ -3523,7 +3523,7 @@ export class MockPluginGateway implements PluginGateway {
       throw err;
     }
     this.plugins.splice(idx, 1);
-    return { pluginId, restartRequired: true };
+    return { pluginId, removalOutcome: "removed", restartRequired: true };
   }
 
   async listRuntimeContributions(): Promise<PluginRuntimeContributionCatalog> {