fix: shift fill_rate percentage and seeder status consistency

fill_rate accessor returned decimal (0.33) instead of percentage (33),
causing progress bars to display at ~1% width. DevSeeder hard-coded
status='full' on EHBO za_dag despite only 1/4 slots filled, and factory
assignments now respect slots_open_for_claiming. Added post-assignment
status auto-correction based on actual fill counts.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/app/Models/Shift.php

@@ -111,7 +111,7 @@ final class Shift extends Model
                 return 0;
             }
 
-            return round($this->filled_slots / $this->slots_total, 2);
+            return (int) round(($this->filled_slots / $this->slots_total) * 100);
         });
     }