Add Sombra Residential LLC client + Server2013 docs

- New clients/sombra-residential/CONTEXT.md (server stub, GuruRMM agent, EOL flag)
- credentials.md: pointer to vault for Administrator password

credentials.md

@@ -530,6 +530,19 @@ export OP_SERVICE_ACCOUNT_TOKEN="op://Infrastructure/Service Account Auth Token:
 
 ---
 
+## Client - Sombra Residential LLC
+
+### Server2013 (primary server)
+- **Hostname:** Server2013
+- **OS:** Windows Server 2012 (build 9200) — name is just a label; **EOL 2023-10-10**
+- **Remote access:** ScreenConnect (ACG SC instance)
+- **Administrator password:** SOPS `clients/sombra-residential/server2013.sops.yaml` (field `credentials.password`)
+- **sysadmin password:** TBD — pending capture
+- **GuruRMM:** Sombra Residential LLC / main office, agent `5383e9c1-56e1-4389-9c89-1991a77bbc3a`
+- **Full context:** `clients/sombra-residential/CONTEXT.md`
+
+---
+
 ## MSP Tools
 
 ### Syncro (PSA/RMM)