Treat missing source dir as warning in validate

Titas-Ghosh · Titas-Ghosh · commit 88138af9f7b2 · 2026-02-14T03:16:07.000+05:30
diff --git a/concore_cli/commands/validate.py b/concore_cli/commands/validate.py
@@ -71,7 +71,7 @@ def finalize():
             info.append(f"Found {len(edges)} edge(s)")
 
         if not source_root.exists():
-            errors.append(f"Source directory not found: {source_root}")
+            warnings.append(f"Source directory not found: {source_root}")
         
         node_labels = []
         for node in nodes:
