fix(cli): local backend CLI always uses launch directory, stops .env sync of TERMINAL_CWD (#19334)

The old CWD heuristic was fooled by:
1. TERMINAL_CWD persisted to .env by `hermes config set terminal.cwd`
2. Inherited TERMINAL_CWD from parent hermes processes
3. Only resolved when config had a placeholder value (not explicit paths)

Fix:
- load_cli_config() unconditionally uses os.getcwd() for local backend
- TERMINAL_CWD always force-exported in CLI mode (overrides stale values)
- Gateway sets _HERMES_GATEWAY=1 marker so lazy cli.py imports don't clobber
- Remove terminal.cwd from config-set .env sync map (prevents re-poisoning)
- Clarify setup wizard label as 'Gateway working directory'

Closes #19214

hermes_cli/config.py

@@ -4675,7 +4675,9 @@ def set_config_value(key: str, value: str):
         "terminal.vercel_runtime": "TERMINAL_VERCEL_RUNTIME",
         "terminal.docker_mount_cwd_to_workspace": "TERMINAL_DOCKER_MOUNT_CWD_TO_WORKSPACE",
         "terminal.docker_run_as_host_user": "TERMINAL_DOCKER_RUN_AS_HOST_USER",
-        "terminal.cwd": "TERMINAL_CWD",
+        # terminal.cwd intentionally excluded — CLI resolves at runtime,
+        # gateway bridges it in gateway/run.py. Persisting to .env causes
+        # stale values to poison child processes.
         "terminal.timeout": "TERMINAL_TIMEOUT",
         "terminal.sandbox_dir": "TERMINAL_SANDBOX_DIR",
         "terminal.persistent_shell": "TERMINAL_PERSISTENT_SHELL",