Default customer to 'internal' when left blank

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

app/routers/ui.py

@@ -221,7 +221,7 @@ async def create_job(
         filename = stl_select
 
     amount = max(1, amount)
-    customer_str = customer.strip() or None
+    customer_str = customer.strip() or "internal"
     job_name = Path(filename).stem if filename else (customer_str or "Unnamed")
 
     # Resolve bracket — auto-create one when printing multiple copies
@@ -320,7 +320,7 @@ def edit_job(
     job = db.query(PrintJob).filter(PrintJob.id == job_id).first()
     if not job:
         raise HTTPException(status_code=404, detail="Job not found")
-    job.customer = customer.strip() or None
+    job.customer = customer.strip() or "internal"
     job.job_material = job_material or None
     job.job_color = job_color or None
     job.priority = bool(priority)