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

website/docs/reference/environment-variables.md

@@ -187,7 +187,7 @@ These variables configure the [Tool Gateway](/docs/user-guide/features/tool-gate
 | `TERMINAL_VERCEL_RUNTIME` | Vercel Sandbox runtime (`node24`, `node22`, `python3.13`) |
 | `TERMINAL_TIMEOUT` | Command timeout in seconds |
 | `TERMINAL_LIFETIME_SECONDS` | Max lifetime for terminal sessions in seconds |
-| `TERMINAL_CWD` | Working directory for all terminal sessions |
+| `TERMINAL_CWD` | Working directory for terminal sessions (gateway/cron only; CLI uses launch dir) |
 | `SUDO_PASSWORD` | Enable sudo without interactive prompt |
 
 For cloud sandbox backends, persistence is filesystem-oriented. `TERMINAL_LIFETIME_SECONDS` controls when Hermes cleans up an idle terminal session, and later resumes may recreate the sandbox rather than keep the same live processes running.