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

gateway/run.py

@@ -316,6 +316,10 @@ def _restart_notification_pending() -> bool:
     return (_hermes_home / ".restart_notify.json").exists()
 
 
+# Mark this process as a gateway so cli.py's module-level load_cli_config()
+# knows not to clobber TERMINAL_CWD if lazily imported.
+os.environ["_HERMES_GATEWAY"] = "1"
+
 _ensure_ssl_certs()
 
 # Add parent directory to path