fix: harden stale import job detection and cancellation cleanup

- Extend stale-job auto-cancel to cover `running` jobs (30 min threshold) in addition to `pending` jobs (5 min), so crashed mid-import workers don't permanently block new imports
- Use `startedAt` instead of `createdAt` when calculating age for running jobs
- Scope `readImportJob` in the SSE loop to the authenticated user's ID to prevent cross-user job reads
- Persist progress counters (`processedItems`, `importedCount`, `skippedCount`, `failedCount`) when a job is cancelled mid-run so the UI shows accurate final stats

packages/core/src/imports/processor.ts

@@ -363,6 +363,10 @@ export async function processImportJob(jobId: string): Promise<void> {
         if (currentStatus?.status === "cancelled") {
           updateImportJobProgress(jobId, {
             finishedAt: new Date(),
+            processedItems: i,
+            importedCount: result.imported,
+            skippedCount: result.skipped,
+            failedCount: result.failed,
             errors: JSON.stringify(result.errors),
             warnings: JSON.stringify(result.warnings),
             currentMessage: "Import cancelled",