recipe-maintainer: public snapshot (secrets + deployment plans removed, single commit)

Sanitized single-commit public mirror of recipe-maintainer.
- Removed test-ssh/.testenv (live creds); added test-ssh/.testenv.example placeholders.
- Removed plans/ and planned-updates/ (deployment-planning docs) so no client/
  deployment domains appear in the public repo.
- All other secret stores were already gitignored.
- docs.coopcloud.tech retained as a submodule (public upstream).

recipe-info/mumble/upstream.md

@@ -0,0 +1,14 @@
+# Mumble Upstream
+
+## Main Project
+
+- **Repository:** https://github.com/mumble-voip/mumble
+- **Releases:** https://github.com/mumble-voip/mumble/releases
+- **Website:** https://www.mumble.info
+
+## Images
+
+| Service | Image | Release Notes |
+|---------|-------|---------------|
+| app | `mumblevoip/mumble-server` | https://github.com/mumble-voip/mumble-docker/releases |
+| web (optional) | `rankenstein/mumble-web` | https://github.com/nickvergessen/mumble-web |