OPC # 0006: OPC Git Trunk-Based management

Co-authored-by: Copilot <copilot@github.com>

ControlPlane.Api/Services/ImageBuildService.cs

@@ -2,6 +2,7 @@ using ControlPlane.Core.Models;
 using ControlPlane.Core.Services;
 using Docker.DotNet;
 using Docker.DotNet.Models;
+using LibGit2Sharp;
 
 namespace ControlPlane.Api.Services;
 
@@ -49,6 +50,14 @@ public class ImageBuildService(
 
         var record = await history.CreateBuildAsync(BuildKind.DockerImage, ImageName);
 
+        // Capture HEAD SHA so the build is traceable back to a specific commit
+        try
+        {
+            using var repo = new Repository(repoRoot);
+            record.CommitSha = repo.Head.Tip?.Sha;
+        }
+        catch { /* not a git repo or no commits yet — CommitSha stays null */ }
+
         try
         {
             var socketUri = config["Docker:Socket"] ?? "npipe://./pipe/docker_engine";