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/code_execution_tool.py

@@ -1020,6 +1020,13 @@ def execute_code(
         if _tz_name:
             child_env["TZ"] = _tz_name
 
+        # Per-profile HOME isolation: redirect system tool configs into
+        # {HERMES_HOME}/home/ when that directory exists.
+        from hermes_constants import get_subprocess_home
+        _profile_home = get_subprocess_home()
+        if _profile_home:
+            child_env["HOME"] = _profile_home
+
         proc = subprocess.Popen(
             [sys.executable, "script.py"],
             cwd=tmpdir,