Add Galaxy repository API and clients

docs/GatewayConfiguration.md

@@ -53,6 +53,11 @@ paths, timeouts, queue sizes, enum values, or protocol values are invalid.
     },
     "Protocol": {
       "WorkerProtocolVersion": 1
+    },
+    "Galaxy": {
+      "ConnectionString": "Server=localhost;Database=ZB;Integrated Security=True;TrustServerCertificate=True;Encrypt=False;",
+      "CommandTimeoutSeconds": 60,
+      "DashboardRefreshIntervalSeconds": 30
     }
   }
 }
@@ -146,9 +151,21 @@ The protocol option is exposed for diagnostics and explicit deployment
 configuration, not for compatibility negotiation. A mismatch fails validation
 at startup.
 
+## Galaxy Options
+
+| Option | Default | Description |
+|--------|---------|-------------|
+| `MxGateway:Galaxy:ConnectionString` | `Server=localhost;Database=ZB;Integrated Security=True;TrustServerCertificate=True;Encrypt=False;` | SQL Server connection string for the Galaxy Repository (`ZB`) used by the `GalaxyRepository` browse RPCs. Override in production via `MxGateway__Galaxy__ConnectionString`. |
+| `MxGateway:Galaxy:CommandTimeoutSeconds` | `60` | Per-command SQL timeout for all Galaxy browse RPCs. |
+| `MxGateway:Galaxy:DashboardRefreshIntervalSeconds` | `30` | Interval between background refreshes of the dashboard Galaxy summary cache. SQL is hit at most once per interval regardless of dashboard render rate. |
+
+See [Galaxy Repository Browse](./GalaxyRepository.md) for the RPC surface and
+behavior.
+
 ## Related Documentation
 
 - [Gateway Process Detailed Design](./gateway-process-design.md)
 - [Gateway Dashboard Detailed Design](./gateway-dashboard-design.md)
 - [Worker Process Launcher](./WorkerProcessLauncher.md)
 - [Worker Frame Protocol](./WorkerFrameProtocol.md)
+- [Galaxy Repository Browse](./GalaxyRepository.md)