fix(oauth,gateway): monotonic deadlines for polling/timeout loops

Widen PR #20314's fix to the other timeout-polling sites in the codebase
that share the same wall-clock-jump bug class. All of these measure elapsed
timeout duration, not civil time, so they belong on time.monotonic().

- hermes_cli/auth.py: auth-store file-lock timeout, Spotify OAuth callback
  wait, Nous portal device-auth token poll.
- hermes_cli/copilot_auth.py: Copilot OAuth device-flow token poll.
- hermes_cli/gateway.py: gateway systemd restart wait.
- hermes_cli/web_server.py: dashboard Codex device-auth user_code wait,
  dashboard Nous device-auth token poll. (sess["expires_at"] stays on
  time.time() — it's a persisted absolute timestamp, not a local
  deadline-polling variable.)
- agent/copilot_acp_client.py: Copilot ACP JSON-RPC request timeout.

hermes_cli/gateway.py

@@ -585,10 +585,10 @@ def _wait_for_systemd_service_restart(
 
     svc = get_service_name()
     scope_label = _service_scope_label(system).capitalize()
-    deadline = time.time() + timeout
+    deadline = time.monotonic() + timeout
     printed_runtime_wait = False
 
-    while time.time() < deadline:
+    while time.monotonic() < deadline:
         props = _read_systemd_unit_properties(system=system)
         active_state = props.get("ActiveState", "")
         sub_state = props.get("SubState", "")