Auto-create todos on print events

- 'Clean build plate on {printer}' after every 3rd completed print per printer
- 'Check filament status' when a roll drops below 100 g after starting a job

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

app/routers/ui.py

@@ -359,6 +359,8 @@ def start_job(job_id: int, printer_id: int = Form(...), db: Session = Depends(ge
                         f"(AMS slot {roll['slot']} — {roll['material']} {roll['color']}, "
                         f"{roll['weight_remaining_g']} g remaining, least-full roll selected)"
                     )))
+                    if roll["weight_remaining_g"] - weight_g < 100:
+                        db.add(Todo(title="Check filament status"))
                 else:
                     db.add(JobLog(job_id=job_id, message=f"FilamentDB: print log failed for roll #{roll['roll_id']}"))
             else:
@@ -422,6 +424,16 @@ def finish_job(job_id: int, db: Session = Depends(get_db)):
         job.printer.status = PrinterStatus.idle
 
     db.add(JobLog(job_id=job_id, message=f"Job finished on {printer_name}"))
+
+    # Every 3rd completed print on this printer → cleaning reminder
+    if job.printer_id:
+        done_count = db.query(PrintJob).filter(
+            PrintJob.printer_id == job.printer_id,
+            PrintJob.status == JobStatus.done,
+        ).count()
+        if (done_count + 1) % 3 == 0:
+            db.add(Todo(title=f"Clean build plate on {printer_name}", printer_id=job.printer_id))
+
     db.commit()
     return RedirectResponse(url=f"/jobs/{job_id}", status_code=HTTP_303_SEE_OTHER)