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/user-guide/configuration.md

@@ -88,7 +88,7 @@ Hermes supports seven terminal backends. Each determines where the agent's shell
 ```yaml
 terminal:
   backend: local    # local | docker | ssh | modal | daytona | vercel_sandbox | singularity
-  cwd: "."          # Working directory ("." = current dir for local, "/root" for containers)
+  cwd: "."          # Gateway/cron working directory (CLI always uses launch dir)
   timeout: 180      # Per-command timeout in seconds
   env_passthrough: []  # Env var names to forward to sandboxed execution (terminal + execute_code)
   singularity_image: "docker://nikolaik/python-nodejs:python3.11-nodejs20"  # Container image for Singularity backend