[wip] cli capability parity

docs/packs/pack-structure.md

@@ -241,12 +241,9 @@ import json
 import sys
 
 def read_stdin_params():
-    """Read parameters from stdin."""
-    content = sys.stdin.read()
-    parts = content.split('---ATTUNE_PARAMS_END---')
-    params = json.loads(parts[0].strip()) if parts[0].strip() else {}
-    secrets = json.loads(parts[1].strip()) if len(parts) > 1 and parts[1].strip() else {}
-    return {**params, **secrets}
+    """Read parameters from stdin. Secrets are already merged into parameters."""
+    content = sys.stdin.read().strip()
+    return json.loads(content) if content else {}
 
 def main():
     params = read_stdin_params()