add dbgate and mssql

docs/decisions.md

@@ -274,6 +274,54 @@ when additional services begin consuming the same secret management approach.
 
 ---
 
+## 2026-06-22 - Deploy Microsoft SQL Server Express Alongside PostgreSQL
+
+Decision:
+
+* Run Microsoft SQL Server 2022 Express alongside PostgreSQL.
+* Attach MSSQL only to the `internal` Docker network.
+* Do not publish port `1433` or route MSSQL through the reverse proxy.
+* Store `MSSQL_SA_PASSWORD` in `/srv/secrets/company.env`.
+
+Reason:
+
+* Support Silver projects that require Microsoft SQL Server compatibility.
+* Allow both database platforms to coexist without exposing database ports.
+
+Status:
+
+```text
+Implemented
+```
+
+---
+
+## 2026-06-22 - Select DbGate for Database Administration
+
+Decision:
+
+* Use DbGate to administer Microsoft SQL Server and PostgreSQL.
+* Connect DbGate to both the `internal` and `proxy` Docker networks.
+* Publish only the DbGate web interface through Nginx Proxy Manager.
+* Require DbGate authentication and HTTPS.
+
+Reason:
+
+* Provides one lightweight, modern browser interface for both database platforms.
+* Keeps PostgreSQL and MSSQL private.
+
+Follow-up:
+
+Move the DbGate password from the server-side Compose configuration to `/srv/secrets/company.env`.
+
+Status:
+
+```text
+Implemented
+```
+
+---
+
 ## Future Decisions
 
 Document future decisions using the following template: