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/matrix-synapse/setup.md

@@ -0,0 +1,25 @@
+# Matrix Synapse — First-Time Setup
+
+## Prerequisites
+
+- DNS: `matrix-synapse.<domain_suffix>` must resolve to the server
+
+## Steps
+
+1. **Create the app:**
+   ```bash
+   abra app new matrix-synapse --server <SERVER> --domain matrix-synapse.<DOMAIN_SUFFIX> --no-input
+   ```
+
+2. **Generate secrets:**
+   ```bash
+   abra app secret generate matrix-synapse.<DOMAIN_SUFFIX> --all -m --no-input
+   ```
+   Save output to `recipe-info/testsecrets/matrix-synapse.<DOMAIN_SUFFIX>`.
+
+3. **Deploy:**
+   ```bash
+   abra app deploy matrix-synapse.<DOMAIN_SUFFIX> --chaos --force --no-input
+   ```
+
+4. **Verify:** curl `https://matrix-synapse.<DOMAIN_SUFFIX>` returns HTTP 200.