Switch Lotus Cinny from nightly dev to stable-release fork workflow

- Replace nightly build script with daily upstream release checker
  (cinny/upstream-check.sh) — posts to Matrix as LotusBot when a new
  cinnyapp/cinny stable release is published
- Add cinny/lotus-build.sh — merges latest release tag into the lotus
  branch, builds, deploys; triggered via !cinny-update webhook
- Fork lives at code.lotusguild.org/LotusGuild/cinny (lotus branch, v4.11.1)
- deploy/hooks-lxc106.json — adds cinny-build webhook endpoint (port 9000)
- Update landing page: "dev branch / nightly" → "Lotus fork / stable releases"
- Set LotusBot avatar on @hookshot_tinker-tickets

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

landing/index.html

@@ -547,15 +547,15 @@
                     <span class="client-desc">Hosted Cinny &mdash; homeserver pre-configured, no setup</span>
                     <span class="tag-row">
                         <span class="tag dim">Desktop &amp; Web</span>
-                        <span class="tag dev">Dev Branch</span>
+                        <span class="tag dev">Lotus Fork</span>
                         <span class="tag voice">Voice &amp; Video Rooms</span>
                         <span class="tag">Discord-like UI</span>
                     </span>
                 </a>
             </div>
             <p class="also-available">
-                Runs the Cinny <strong>dev branch</strong> &mdash; latest beta features, updated nightly.
-                Prefer stable? Use <a href="https://cinny.in" target="_blank" rel="noopener">cinny.in</a> and set homeserver to <code style="font-size:0.8em;color:#e88;">matrix.lotusguild.org</code>.
+                A custom Lotus Guild fork of Cinny, based on stable releases.
+                Prefer the official client? Use <a href="https://cinny.in" target="_blank" rel="noopener">cinny.in</a> and set homeserver to <code style="font-size:0.8em;color:#e88;">matrix.lotusguild.org</code>.
             </p>
 
             <div class="space-join">
@@ -665,7 +665,7 @@
             <thead>
                 <tr>
                     <th></th>
-                    <th class="ours">Cinny<small>chat.lotusguild.org<br>dev branch</small></th>
+                    <th class="ours">Cinny<small>chat.lotusguild.org<br>Lotus fork</small></th>
                     <th>Element X<small>iOS &amp; Android</small></th>
                     <th>FluffyChat<small>All platforms</small></th>
                     <th>Commet<small>Android / Win / Linux</small></th>