fix: refresh systemd unit on gateway boot (not just start/restart) (#19684)

The resilient restart settings from PR #18639 only took effect when
the gateway was started via `hermes gateway start` or `hermes gateway
restart` — both of which call refresh_systemd_unit_if_needed() which
writes the new unit and runs daemon-reload.

However, when the gateway self-restarts via exit-code-75 (stale-code
detection after `hermes update`, or the /restart command), systemd
respawns the process directly without going through any CLI function.
The unit file on disk stays stale, and systemd keeps using the old
cached settings (StartLimitBurst=5, RestartSec=30) until someone
manually runs `hermes gateway restart`.

This meant that after PR #18639 was deployed, users who never ran
`hermes gateway restart` manually were still vulnerable to the
permanent-death-on-network-outage bug.

Fix: call refresh_systemd_unit_if_needed() at the top of run_gateway()
(the foreground entry point that systemd's ExecStart invokes). This
ensures that on every boot — whether triggered by systemd restart,
exit-75 respawn, or manual foreground run — the unit definition and
daemon state are current. The call is best-effort (exceptions caught)
and a no-op when the unit is already current (one stat + string compare).

hermes_cli/gateway.py

@@ -2492,6 +2492,20 @@ def run_gateway(verbose: int = 0, quiet: bool = False, replace: bool = False):
                  hasn't fully exited yet.
     """
     sys.path.insert(0, str(PROJECT_ROOT))
+
+    # Refresh the systemd unit definition on every boot so that restart
+    # settings (RestartSec, StartLimitIntervalSec, etc.) stay current even
+    # when the process was respawned via exit-code-75 (stale-code or
+    # /restart) rather than through `hermes gateway restart` which already
+    # calls refresh_systemd_unit_if_needed().  Without this, a code update
+    # that ships new unit settings won't take effect until the next manual
+    # `hermes gateway start/restart` — leaving the gateway vulnerable to
+    # the exact failure mode the new settings were meant to prevent.
+    if supports_systemd_services():
+        try:
+            refresh_systemd_unit_if_needed(system=False)
+        except Exception:
+            pass  # best-effort; don't block gateway startup
     
     from gateway.run import start_gateway