Add process_repo docstring

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: sylwia-budzynska

src/seclab_taskflows/mcp_servers/utils.py

@@ -2,4 +2,14 @@
 # SPDX-License-Identifier: MIT
 
 def process_repo(owner, repo):
+    """
+    Normalize repository identifier to lowercase format 'owner/repo'.
+
+    Args:
+        owner (str): The owner of the repository.
+        repo (str): The name of the repository.
+
+    Returns:
+        str: The normalized repository identifier in lowercase.
+    """
     return f"{owner}/{repo}".lower()