feat: integrate client and server sharing workflows

server/src/WebDrop.Api/ApiContract.cs

@@ -0,0 +1,7 @@
+namespace WebDrop.Api;
+
+public static class ApiContract
+{
+    // Keep this aligned with contracts/api-contract.json and docs/openapi.yaml.
+    public const string Version = "1.0.0";
+}