fix: per-profile subprocess HOME isolation (#4426) (#7357)

Isolate system tool configs (git, ssh, gh, npm) per profile by injecting
a per-profile HOME into subprocess environments only.  The Python
process's own os.environ['HOME'] and Path.home() are never modified,
preserving all existing profile infrastructure.

Activation is directory-based: when {HERMES_HOME}/home/ exists on disk,
subprocesses see it as HOME.  The directory is created automatically for:
- Docker: entrypoint.sh bootstraps it inside the persistent volume
- Named profiles: added to _PROFILE_DIRS in profiles.py

Injection points (all three subprocess env builders):
- tools/environments/local.py _make_run_env() — foreground terminal
- tools/environments/local.py _sanitize_subprocess_env() — background procs
- tools/code_execution_tool.py child_env — execute_code sandbox

Single source of truth: hermes_constants.get_subprocess_home()

Closes #4426

tools/environments/local.py

@@ -129,6 +129,12 @@ def _sanitize_subprocess_env(base_env: dict | None, extra_env: dict | None = Non
         elif key not in _HERMES_PROVIDER_ENV_BLOCKLIST or _is_passthrough(key):
             sanitized[key] = value
 
+    # Per-profile HOME isolation for background processes (same as _make_run_env).
+    from hermes_constants import get_subprocess_home
+    _profile_home = get_subprocess_home()
+    if _profile_home:
+        sanitized["HOME"] = _profile_home
+
     return sanitized
 
 
@@ -195,6 +201,15 @@ def _make_run_env(env: dict) -> dict:
     existing_path = run_env.get("PATH", "")
     if "/usr/bin" not in existing_path.split(":"):
         run_env["PATH"] = f"{existing_path}:{_SANE_PATH}" if existing_path else _SANE_PATH
+
+    # Per-profile HOME isolation: redirect system tool configs (git, ssh, gh,
+    # npm …) into {HERMES_HOME}/home/ when that directory exists.  Only the
+    # subprocess sees the override — the Python process keeps the real HOME.
+    from hermes_constants import get_subprocess_home
+    _profile_home = get_subprocess_home()
+    if _profile_home:
+        run_env["HOME"] = _profile_home
+
     return run_env