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>

systemd/cinny-dev-update.cron

@@ -1 +0,0 @@
-0 3 * * * root /usr/local/bin/cinny-dev-update.sh

systemd/cinny-upstream-check.cron

@@ -0,0 +1 @@
+0 12 * * * root /usr/local/bin/cinny-upstream-check.sh