jiti (the TS/ESM loader used for plugin loading) converts imports to
CJS require() internally. Three dependencies (@buape/carbon,
osc-progress, @mariozechner/pi-coding-agent) ship export maps with
only an "import" condition and no "default" or "require" fallback,
causing ERR_PACKAGE_PATH_NOT_EXPORTED at runtime. This silently breaks
all plugin loading for any plugin importing from openclaw/plugin-sdk.
Add a postinstall script that walks node_modules and adds the missing
"default" export condition to any package whose exports have "import"
but neither "default" nor "require". The patch is idempotent, has zero
runtime cost, and becomes a no-op if upstream packages add CJS support.
