Revert to Repository.GetAllTags with fallback date handling

Reverted from Git.Reference.GetAll back to Repository.GetAllTags as suggested.
The implementation now:
- Uses Repository.GetAllTags to fetch all tags
- Tries Git.Tag.Get to get annotated tag date
- Falls back to Repository.Commit.Get for commit date if tag object doesn't exist
  or doesn't have a date
- Simpler approach that handles both annotated and lightweight tags with
  appropriate fallback logic

Co-authored-by: Malcolmnixon <1863707+Malcolmnixon@users.noreply.github.com>

Author: Copilot

src/DemaConsulting.BuildMark/RepoConnectors/GitHubRepoConnector.cs

@@ -101,12 +101,12 @@ private static string ValidateTag(string tag)
     /// <item>Fetch all commits on the current branch using Octokit Repository.Commit.GetAll API (newest to oldest)</item>
     /// <item>Start collecting commits once we reach the current commit SHA</item>
     /// <item>Continue collecting all older commits (the history) until pagination completes</item>
-    /// <item>Fetch all tag references using Octokit Git.Reference.GetAll API with "tags" prefix</item>
+    /// <item>Fetch all repository tags using Octokit Repository.GetAllTags API</item>
     /// <item>Filter tags to only those whose commit is in the branch history</item>
-    /// <item>For each valid tag, get the tag date (annotated tag date or commit date)</item>
+    /// <item>For each valid tag, try to get annotated tag date via Git.Tag.Get, fall back to commit date if not available</item>
     /// <item>Sort tags by date and return as Version objects</item>
     /// </list>
-    /// This approach works with shallow checkouts unlike git commands and uses Git References API for reliable tag discovery.
+    /// This approach works with shallow checkouts unlike git commands.
     /// </remarks>
     public override async Task<List<Version>> GetTagHistoryAsync()
     {
@@ -157,77 +157,49 @@ public override async Task<List<Version>> GetTagHistoryAsync()
             page++;
         }
 
-        // Get all tag references from the repository using Git References API
-        var allTagRefs = await _client.Git.Reference.GetAll(_owner, _repo);
+        // Get all tags from the repository
+        var allTags = await _client.Repository.GetAllTags(_owner, _repo);
 
-        // Filter to only tag references and tags on commits in the branch history
+        // Filter tags that are on commits in the branch history
         var tagsOnBranch = new List<(Version version, DateTimeOffset date)>();
 
-        foreach (var tagRef in allTagRefs)
+        foreach (var tag in allTags)
         {
-            // Only process tag references (refs/tags/*)
-            if (!tagRef.Ref.StartsWith("refs/tags/", StringComparison.Ordinal))
-            {
-                continue;
-            }
-            
-            // Extract tag name from ref (refs/tags/v1.0.0 -> v1.0.0)
-            var tagName = tagRef.Ref.Substring("refs/tags/".Length);
-            
             // Try to parse as a version
-            var version = Version.TryCreate(tagName);
+            var version = Version.TryCreate(tag.Name);
             if (version == null)
             {
                 continue;
             }
 
-            // Get the commit SHA from the tag reference
-            var commitSha = tagRef.Object.Sha;
-            
-            // For annotated tags, we need to dereference to get the actual commit
-            if (tagRef.Object.Type == TaggedType.Tag)
-            {
-                try
-                {
-                    var tagObject = await _client.Git.Tag.Get(_owner, _repo, tagRef.Object.Sha);
-                    commitSha = tagObject.Object.Sha;
-                }
-                catch
-                {
-                    // If we can't dereference, skip this tag
-                    continue;
-                }
-            }
-            
             // Check if this tag's commit is in the branch history
-            if (!branchCommits.Contains(commitSha))
+            if (!branchCommits.Contains(tag.Commit.Sha))
             {
                 continue;
             }
 
-            // Get the tag date
+            // Get the tag date - try Git.Tag.Get first for annotated tags, fall back to commit date
             DateTimeOffset tagDate;
             try
             {
-                // If this is an annotated tag, get the tagger date
-                if (tagRef.Object.Type == TaggedType.Tag)
+                // Try to get the annotated tag object
+                var tagObject = await _client.Git.Tag.Get(_owner, _repo, tag.Commit.Sha);
+                tagDate = tagObject.Tagger.Date;
+            }
+            catch
+            {
+                // Fall back to commit date if tag object doesn't exist or doesn't have a date
+                try
                 {
-                    var tagObject = await _client.Git.Tag.Get(_owner, _repo, tagRef.Object.Sha);
-                    tagDate = tagObject.Tagger.Date;
+                    var commit = await _client.Repository.Commit.Get(_owner, _repo, tag.Commit.Sha);
+                    tagDate = commit.Commit.Author.Date;
                 }
-                else
+                catch
                 {
-                    // Lightweight tag - get commit date
-                    var commit = await _client.Repository.Commit.Get(_owner, _repo, commitSha);
-                    tagDate = commit.Commit.Author.Date;
+                    // If we can't get either, skip this tag
+                    continue;
                 }
             }
-            catch
-            {
-                // Fall back to commit date if we can't get the tag object
-                var commit = await _client.Repository.Commit.Get(_owner, _repo, commitSha);
-                tagDate = commit.Commit.Author.Date;
-            }
 
             tagsOnBranch.Add((version, tagDate));
         }