fix(docker): add explicit env allowlist for container credentials (#1436)

Docker terminal sessions are secret-dark by default. This adds
terminal.docker_forward_env as an explicit allowlist for env vars
that may be forwarded into Docker containers.

Values resolve from the current shell first, then fall back to
~/.hermes/.env. Only variables the user explicitly lists are
forwarded — nothing is auto-exposed.

Cherry-picked from PR #1449 by @teknium1, conflict-resolved onto
current main.

Fixes #1436
Supersedes #1439

hermes_cli/config.py

@@ -118,6 +118,7 @@ DEFAULT_CONFIG = {
         "cwd": ".",  # Use current directory
         "timeout": 180,
         "docker_image": "nikolaik/python-nodejs:python3.11-nodejs20",
+        "docker_forward_env": [],
         "singularity_image": "docker://nikolaik/python-nodejs:python3.11-nodejs20",
         "modal_image": "nikolaik/python-nodejs:python3.11-nodejs20",
         "daytona_image": "nikolaik/python-nodejs:python3.11-nodejs20",