feat: share preflight authenticated session across agents (#345)

* feat(auth): reuse preflight's authenticated session across agents

* fix(preflight): verify saved auth state parses and has cookies or origins

* fix(prompts): strip shared-session block when no auth is configured

* fix(shannon): store shared auth state in the per-session audit dir

* fix(prompts): write stub auth-state in pipeline-testing preflight

* fix(preflight): clear stale auth-state.json before validate-authentication

* fix(preflight): drop auth-state.json on workflow completion

* docs(claude): refresh auth-state.json description for new layout and cleanup

* refactor(prompts): drop unused PLAYWRIGHT_SESSION resolve in login instructions

* style(prompts): collapse verifySavedAuthState signature per biome

* refactor(prompts): require AUTH_STATE_FILE on authenticated runs

* style(prompts): trim numbered-step comments back to step headers

apps/worker/src/temporal/activities.ts

@@ -22,7 +22,7 @@ import { writePlaywrightStealthConfig } from '../ai/playwright-config-writer.js'
 import { writeUserSettingsForCodePathAvoids } from '../ai/settings-writer.js';
 import { AuditSession } from '../audit/index.js';
 import type { ResumeAttempt } from '../audit/metrics-tracker.js';
-import { generateSessionJsonPath, type SessionMetadata } from '../audit/utils.js';
+import { authStateFile, generateSessionJsonPath, type SessionMetadata } from '../audit/utils.js';
 import type { WorkflowSummary } from '../audit/workflow-logger.js';
 import type { CheckpointContext } from '../interfaces/checkpoint-provider.js';
 import { DEFAULT_DELIVERABLES_SUBDIR, deliverablesDir } from '../paths.js';
@@ -926,7 +926,15 @@ export async function logWorkflowComplete(input: ActivityInput, summary: Workflo
   // 5. Write completion entry to workflow.log
   await auditSession.logWorkflowComplete(cumulativeSummary);
 
-  // 6. Clean up container
+  // 6. Drop the authenticated browser session
+  try {
+    await fs.rm(authStateFile(sessionMetadata), { force: true });
+  } catch (error) {
+    const detail = error instanceof Error ? error.message : String(error);
+    console.warn(`Failed to clean up auth-state.json: ${detail}`);
+  }
+
+  // 7. Clean up container
   removeContainer(workflowId);
 }