Fix optimized letter case

wai_service.py

@@ -93,7 +93,9 @@ def handler(payload: dict) -> str:
     # sensible defaults
     cfg.render_size = getattr(cfg, "render_size", 384)   # <= set here
     cfg.word = cfg.word.upper()
-    cfg.optimized_letter = getattr(cfg, "optimized_letter", cfg.word[-1])
+    cfg.optimized_letter = getattr(cfg, "optimized_letter", cfg.word[-1]).upper()
+    cfg.letter = f"{cfg.font}_{cfg.optimized_letter}_scaled"
+    cfg.target = f"code/data/init/{cfg.letter}"
     if getattr(cfg.diffusion, "model", ...) is Ellipsis:
         cfg.diffusion.model = "runwayml/stable-diffusion-v1-5"