feat(monitoring): add update-run log, fix scheduler skipping stale customer containers

The automatic scheduler only recreated customer containers when it had just
found a NEW image on Docker Hub. If an image was already pulled locally
(e.g. from an earlier manual pull, or auto-apply was off at the time) but
customer containers hadn't been recreated yet, the daily check reported
"already up to date" and silently never touched those customers again —
the recreate step needs to run independently of whether Hub had anything
new, based on each customer's actual container-vs-local-image state.

Also adds a persistent UpdateRunLog: every scheduled and manual pull/update
run now records per-image pull results and per-customer recreate results,
visible in Monitoring > Update Log, instead of only existing in container
logs.

static/index.html

@@ -1260,6 +1260,19 @@
                         <p class="text-muted mb-0" data-i18n="monitoring.clickCheckUpdates">Click "Check for Updates" to compare local images with Docker Hub.</p>
                     </div>
                 </div>
+
+                <!-- Update Run Log -->
+                <div class="card shadow-sm mt-4">
+                    <div class="card-header d-flex justify-content-between align-items-center">
+                        <span><i class="bi bi-clock-history me-2"></i><span data-i18n="monitoring.updateLogTitle">Update Log</span></span>
+                        <button class="btn btn-outline-secondary btn-sm" onclick="loadUpdateLog()" id="btn-refresh-update-log">
+                            <i class="bi bi-arrow-clockwise me-1"></i><span data-i18n="common.refresh">Refresh</span>
+                        </button>
+                    </div>
+                    <div class="card-body" id="update-log-body">
+                        <p class="text-muted mb-0" data-i18n="common.loading">Loading...</p>
+                    </div>
+                </div>
             </div>
         </div>
     </div>