fix(numbering): release project number on order delete + harden split tests + accurate settings preview

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/services/orders.service.ts

@@ -6,6 +6,7 @@ import {
   releaseSharedNumber,
   isOrderNumberTaken,
   generateProjectNumber,
+  releaseProjectNumber,
 } from "./numbering.service";
 import { NasFileManager } from "./nas-file-manager";
 
@@ -731,6 +732,21 @@ export async function deleteOrder(id: number, deleteFiles = false) {
     : new Date().getFullYear();
   await releaseSharedNumber(year, existing.order_number ?? undefined);
 
+  // Release each deleted project's OWN number from the dedicated `project`
+  // sequence. Auto-created projects now draw a distinct number from the
+  // `project` pool (not the order's `shared` number), so deleting the order
+  // must release the project number too — otherwise the highest project number
+  // leaves a permanent gap. Use each project's OWN created_at year: project
+  // numbers embed {YY} and the sequence is (type, year)-keyed, so the order's
+  // year could decrement the wrong row. Best-effort, post-commit, mirroring the
+  // shared release above — releaseSequence row-locks and only decrements when
+  // the deleted number is the current highest, so this is safe/idempotent.
+  for (const p of linkedProjects) {
+    if (!p.project_number) continue;
+    const projYear = p.created_at ? new Date(p.created_at).getFullYear() : year;
+    await releaseProjectNumber(projYear, p.project_number);
+  }
+
   return { data: { id, order_number: existing.order_number } };
 }