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

hermes_cli/profiles.py

@@ -42,6 +42,11 @@ _PROFILE_DIRS = [
     "plans",
     "workspace",
     "cron",
+    # Per-profile HOME for subprocesses: isolates system tool configs (git,
+    # ssh, gh, npm …) so credentials don't bleed between profiles.  In Docker
+    # this also ensures tool configs land inside the persistent volume.
+    # See hermes_constants.get_subprocess_home() and issue #4426.
+    "home",
 ]
 
 # Files copied during --clone (if they exist in the source)