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/main.py

@@ -2971,6 +2971,17 @@ def cmd_update(args):
         print()
         print("✓ Code updated!")
         
+        # After git pull, source files on disk are newer than cached Python
+        # modules in this process.  Reload hermes_constants so that any lazy
+        # import executed below (skills sync, gateway restart) sees new
+        # attributes like display_hermes_home() added since the last release.
+        try:
+            import importlib
+            import hermes_constants as _hc
+            importlib.reload(_hc)
+        except Exception:
+            pass  # non-fatal — worst case a lazy import fails gracefully
+        
         # Sync bundled skills (copies new, updates changed, respects user deletions)
         try:
             from tools.skills_sync import sync_skills