Two related fixes for remote terminal backends (Modal/Docker):
1. NEW: Credential file mounting system
Skills declare required_credential_files in frontmatter. Files are
mounted into Docker (read-only bind mounts) and Modal (mounts at
creation + sync via exec on each command for mid-session changes).
Google Workspace skill updated with the new field.
2. FIX: Docker backend now includes env_passthrough vars
Skills that declare required_environment_variables (e.g. Notion with
NOTION_API_KEY) register vars in the env_passthrough system. The
local backend checked this, but Docker's forward_env was a separate
disconnected list. Now Docker exec merges both sources, so
skill-declared env vars are forwarded into containers automatically.
This fixes the reported issue where NOTION_API_KEY in ~/.hermes/.env
wasn't reaching the Docker container despite being registered via
the Notion skill's prerequisites.
Closes#3665
7a3682ac3f