feat(deployment): DeployToSiteAsync for single-site artifact deployment

Claude-Session: https://claude.ai/code/session_01MtdgwpEeCUn6cUA5f1LMPj

src/ZB.MOM.WW.ScadaBridge.DeploymentManager/ArtifactDeploymentService.cs

@@ -2,6 +2,7 @@ using System.Text.Json;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using ZB.MOM.WW.ScadaBridge.Commons.Entities.Deployment;
+using ZB.MOM.WW.ScadaBridge.Commons.Entities.Sites;
 using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Repositories;
 using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Services;
 using ZB.MOM.WW.ScadaBridge.Commons.Messages.Artifacts;
@@ -232,6 +233,38 @@ public class ArtifactDeploymentService
         if (sites.Count == 0)
             return Result<ArtifactDeploymentSummary>.Failure("No sites configured.");
 
+        return await DeployCoreAsync(sites, user, cancellationToken);
+    }
+
+    /// <summary>
+    /// Deploys system-wide artifacts to a single site (management-API --site-id path).
+    /// </summary>
+    /// <param name="siteId">The database identifier of the target site.</param>
+    /// <param name="user">The user initiating the deployment.</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A summary of the artifact deployment result for the single site.</returns>
+    public async Task<Result<ArtifactDeploymentSummary>> DeployToSiteAsync(
+        int siteId,
+        string user,
+        CancellationToken cancellationToken = default)
+    {
+        var site = await _siteRepo.GetSiteByIdAsync(siteId, cancellationToken);
+        if (site is null)
+            return Result<ArtifactDeploymentSummary>.Failure($"Site with ID {siteId} not found.");
+
+        return await DeployCoreAsync([site], user, cancellationToken);
+    }
+
+    /// <summary>
+    /// Core deployment path shared by the all-sites and single-site entry points.
+    /// Builds a per-site command with that site's data connections and deploys to
+    /// every supplied site under one logical deployment id.
+    /// </summary>
+    private async Task<Result<ArtifactDeploymentSummary>> DeployCoreAsync(
+        IReadOnlyList<Site> sites,
+        string user,
+        CancellationToken cancellationToken)
+    {
         var deploymentId = Guid.NewGuid().ToString("N");
         var perSiteResults = new Dictionary<string, SiteArtifactResult>();