fix(FN-2364): harden diagnostics context and plugin reload imports

- Add explicit operation metadata to agent-generation and ai-session-store diagnostics for cleanup, recovery, and scheduled cleanup paths
- Extend dashboard guardrail coverage to explicitly enforce diagnostics protection for agent-generation.ts and ai-session-store.ts
- Stabilize plugin module reload imports by using temporary reload files with deterministic file URLs and cache updates
- Tighten CLI Vitest workspace cleanup to safely skip missing hidden dist directories during restore

packages/dashboard/src/agent-generation.ts

@@ -215,6 +215,8 @@ function cleanupExpiredSessions(): void {
     diagnostics.info("Cleanup completed", {
       cleanedSessions,
       cleanedRateLimits,
+      ttlMs: SESSION_TTL_MS,
+      rateLimitWindowMs: RATE_LIMIT_WINDOW_MS,
       operation: "cleanup-expired",
     });
   }