Add application configuration inspection commands

docs/integrations/subprocess.md

@@ -17,6 +17,15 @@ Pass required API-key environment variables through the child environment. Do
 not place raw API keys in arguments. Keep the environment limited to the values
 needed for the selected profile.
 
+For application-only preflight, invoke `scriptorium config validate`; it exits
+0 with empty stdout when the application configuration loads, but does not
+prove that Promptkit sources or credentials are usable. `config show` emits
+resolved YAML and `config sources` emits newline-terminated JSON provenance.
+All three use the same source selection and explicit overrides as execution
+commands and require separate stderr capture for diagnostics. Their output can
+include source paths, identifiers, credential reference names, and ordinary
+backend parameters; treat it as potentially sensitive.
+
 ## Streams And Output Ownership
 
 Capture stdout and stderr separately. Stdout contains the requested artifact or