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).

maintained-recipes

@@ -0,0 +1,18 @@
+cryptpad
+lasuite-drive
+lasuite-docs
+lasuite-meet
+matrix-synapse
+keycloak
+bluesky-pds
+mumble
+immich
+mailu
+custom-html
+mattermost-lts
+n8n
+ghost
+drone
+plausible
+uptime-kuma
+discourse