* feat(cli): run agent exec against the ambient config, composed in memory
Exec previously ignored the operator's config entirely, so a one-shot turn
could not reach configured providers, credentials, or agentRuntime harness
selection. It now layers config the way other folder-scoped coding CLIs do.
The composed config is published as this process's runtime snapshot rather
than serialized to a temp file and re-read through OPENCLAW_CONFIG_PATH. The
snapshot is the only in-process config cache, so the file only ever fed it --
while writing env-substituted provider keys to disk where the run's own exec
tool could read them.
* fix(cli): resolve exec stored credentials from the configured agent dir
* chore(scripts): allow agent exec the file-scoped config loader at its process boundary
* test(cli): cover the exec credential default and pinned-config flags
d6f9affe79