fix: align image-gen defaults (#880) (thanks @mkbehr)

skills/openai-image-gen/SKILL.md

@@ -66,6 +66,6 @@ Different models support different parameter values. The script automatically se
 
 ## Output
 
-- `*.png` images
+- `*.png`, `*.jpeg`, or `*.webp` images (output format depends on model + `--output-format`)
 - `prompts.json` (prompt → file mapping)
 - `index.html` (thumbnail gallery)

skills/openai-image-gen/scripts/gen.py

@@ -68,7 +68,7 @@ def get_model_defaults(model: str) -> tuple[str, str]:
         # quality will be ignored
         return ("1024x1024", "standard")
     elif model == "dall-e-3":
-        return ("1024x1024", "hd")
+        return ("1024x1024", "standard")
     else:
         # GPT image or future models
         return ("1024x1024", "high")