fix(deploy): rsync --delete was wiping .auth.json; preserve it (+ siblings)

Symptom: after any commit / deploy on this box, the WebUI would log
users out ~60 seconds after they logged back in. Looked like a
short session timeout; was actually the auth file being deleted.

Cause: my recent update.sh change added --delete to the frontend
rsync so source-tree file removals propagate to the live install.
Excludes only protected data/. .auth.json sits at the top of
frontend/ (never in the source repo — it's the persisted credentials
+ JWT secret), so --delete nuked it on every deploy. The next
container start regenerated it with a fresh secret; all existing
cookies (signed with the old secret) became invalid. The dashboard's
60-second auto-refresh hits /data/system/*.json which is auth-gated,
gets 401, and the global 401 interceptor in auth-manager.js shows
the re-login overlay. Hence 'logged out after 60 seconds'.

Fix: extend the rsync exclude list with:
  --exclude '.*'       (any top-level dotfile — covers .auth.json
                        and future runtime state of the same shape)
  --exclude '*.lock'   (lockfiles like setup.lock if any ever land
                        outside data/)
  --exclude '*.bak'    (backup files from manual edits)

data/ exclude kept. JWT lifetime stays at 30 days as designed.

Also: feat(webui): icon on the 'Open Locations' button in the
backup → Migrate tab's empty state. Matches the location-pin icon
used by the sidebar's Locations entry so the visual carries over
when the user clicks through.

Signed-off-by: librelad <librelad@digitalangels.vip>

containers/libreportal/frontend/html/backup-content.html

@@ -162,7 +162,13 @@
                   No backups from other hosts visible in any enabled location.<br>
                   Add a <strong>shared backup location</strong> on both hosts to enable cross-host migrate.
                   <div style="margin-top:12px">
-                    <button type="button" class="backup-primary-btn" data-action="go-to-locations">Open Locations</button>
+                    <button type="button" class="backup-primary-btn" data-action="go-to-locations">
+                      <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+                        <path d="M21 10c0 7-9 13-9 13s-9-6-9-13a9 9 0 0 1 18 0z"></path>
+                        <circle cx="12" cy="10" r="3"></circle>
+                      </svg>
+                      Open Locations
+                    </button>
                   </div>
                 </div>
               </div>