fix: use in-memory startedAt for cron job log to survive DB restore

The auto-import wipes the database, destroying the cronJobLog record
created at the start of the job. Now duration is calculated from a
local variable instead of querying the DB, and if the record is gone
a fresh log entry is created in the restored database.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/db/shared/helpers/decimal-helpers.ts

@@ -1,7 +1,8 @@
 import * as z from 'zod';
 
-import { Prisma } from '../../generated/prisma';
-import Decimal from 'decimal.js';
+import type { Prisma } from '../../generated/prisma';
+
+import Decimal from "decimal.js";
 
 // DECIMAL HELPERS
 //------------------------------------------------------
@@ -23,7 +24,7 @@ export const isValidDecimalInput = (
   if (v === undefined || v === null) return false;
   return (
     // Explicit instance checks first
-    v instanceof Prisma.Decimal ||
+    v instanceof Decimal ||
     // If Decimal.js is present and imported by the generator, this symbol exists at runtime
     // eslint-disable-next-line @typescript-eslint/ban-ts-comment
     // @ts-ignore - Decimal may be undefined when not installed; codegen controls the import