fix: make display_hermes_home imports lazy to prevent ImportError during hermes update (#3776)

When a user runs 'hermes update', the Python process caches old modules
in sys.modules.  After git pull updates files on disk, lazy imports of
newly-updated modules fail because they try to import display_hermes_home
from the cached (old) hermes_constants which doesn't have the function.

This specifically broke the gateway auto-restart in cmd_update — importing
hermes_cli/gateway.py triggered the top-level 'from hermes_constants
import display_hermes_home' against the cached old module.  The ImportError
was silently caught, so the gateway was never restarted after update.

Users with a running gateway then hit the ImportError on their next
Telegram/Discord message when the stale gateway process lazily loaded
run_agent.py (new version) which also had the top-level import.

Fixes:
- hermes_cli/gateway.py: lazy import at call site (line 940)
- run_agent.py: lazy import at call site (line 6927)
- tools/terminal_tool.py: lazy imports at 3 call sites
- tools/tts_tool.py: static schema string (no module-level call)
- hermes_cli/auth.py: lazy import at call site (line 2024)
- hermes_cli/main.py: reload hermes_constants after git pull in cmd_update

Also fixes 4 pre-existing test failures in test_parse_env_var caused by
NameError on display_hermes_home in terminal_tool.py.

hermes_cli/auth.py

@@ -38,7 +38,7 @@ import httpx
 import yaml
 
 from hermes_cli.config import get_hermes_home, get_config_path
-from hermes_constants import OPENROUTER_BASE_URL, display_hermes_home
+from hermes_constants import OPENROUTER_BASE_URL
 
 logger = logging.getLogger(__name__)
 
@@ -2021,7 +2021,8 @@ def _login_openai_codex(args, pconfig: ProviderConfig) -> None:
     config_path = _update_config_for_provider("openai-codex", creds.get("base_url", DEFAULT_CODEX_BASE_URL))
     print()
     print("Login successful!")
-    print(f"  Auth state: {display_hermes_home()}/auth.json")
+    from hermes_constants import display_hermes_home as _dhh
+    print(f"  Auth state: {_dhh()}/auth.json")
     print(f"  Config updated: {config_path} (model.provider=openai-codex)")