feat: add saveSession flag to create scenario runs

- Add optional `saveSession` boolean parameter to CreateScenarioRunDto
- Add `saveSession` column to ScenarioRunEntity
- When saveSession=true and run completes, preserve the browser context as a named explore session instead of closing it
- Session name follows pattern: run-{runId}
- Automatically extracts token and localStorage for session persistence
- Injected SessionService and SessionContextService into ScenarioSchedulerService
- Updated MCP run_scenario tool to accept saveSession parameter
- Updated UI run dialog with checkbox to enable session preservation
- Client API updated to pass saveSession flag

client/src/api/client.ts

@@ -192,10 +192,10 @@ export const scenarios = {
   remove(id: string): Promise<void> {
     return request(`/scenarios/${id}`, { method: 'DELETE' });
   },
-  run(id: string, environmentId: string): Promise<ScenarioRun> {
+  run(id: string, environmentId: string, saveSession?: boolean): Promise<ScenarioRun> {
     return request(`/scenarios/${id}/run`, {
       method: 'POST',
-      body: JSON.stringify({ environmentId }),
+      body: JSON.stringify({ environmentId, saveSession }),
     });
   },
   getRun(scenarioId: string, runId: string): Promise<ScenarioRunDetail> {