fix(skills): robustify load_state_json against lone surrogates

Implement a clean_surrogates helper inside lib.sh's load_state_json function
to recursively replace lone surrogates (e.g. from partial TUI screen dumps)
with replacement chars before printing, preventing UnicodeEncodeError on stdout.

.agents/skills/lib.sh

@@ -145,6 +145,16 @@ try:
             d = yaml.safe_load(f) or {}
 except Exception:
     pass
+# Clean lone surrogates to prevent UnicodeEncodeError on stdout print
+def clean_surrogates(obj):
+    if isinstance(obj, str):
+        return obj.encode('utf-8', errors='replace').decode('utf-8')
+    elif isinstance(obj, dict):
+        return {k: clean_surrogates(v) for k, v in obj.items()}
+    elif isinstance(obj, list):
+        return [clean_surrogates(x) for x in obj]
+    return obj
+d = clean_surrogates(d)
 print(json.dumps(d, ensure_ascii=False))
 PYEOF
 }