feat: axl add supports using tags with no releases (#927)

Author: thesayyn

crates/axl-runtime/src/builtins/aspect/axl_add.axl

@@ -151,13 +151,32 @@ def fetch_release_by_tag(ctx: TaskContext, owner: str, repo: str, tag: str) -> d
     response = ctx.http().get(url = url, headers = get_github_headers()).block()
 
     if response.status == 404:
-        fail("Release " + tag + " not found in " + owner + "/" + repo)
+        # Release not found - try to verify the tag exists and use it directly
+        return fetch_tag_as_release(ctx, owner, repo, tag)
 
     if response.status != 200:
         fail("Failed to fetch release info: HTTP " + str(response.status))
 
     return json.decode(response.body)
 
+def fetch_tag_as_release(ctx: TaskContext, owner: str, repo: str, tag: str) -> dict:
+    """Fetch tag info and create a synthetic release object for tags without releases."""
+    # Check if the tag exists by trying to fetch it
+    url = "https://api.github.com/repos/" + owner + "/" + repo + "/git/refs/tags/" + tag
+    response = ctx.http().get(url = url, headers = get_github_headers()).block()
+
+    if response.status == 404:
+        fail("Tag " + tag + " not found in " + owner + "/" + repo)
+
+    if response.status != 200:
+        fail("Failed to fetch tag info: HTTP " + str(response.status))
+
+    # Create a synthetic release object with the tag name
+    return {
+        "tag_name": tag,
+        "author": {"login": "unknown"},
+    }
+
 def compute_integrity(ctx: TaskContext, url: str, temp_file: str) -> str:
     """
     Download a file and compute its SHA512 integrity hash in SSRI format.