Fix Field.select helper to remove dots from select values (strict snake_case)

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

packages/spec/src/data/field.zod.ts

@@ -265,7 +265,7 @@ export const Field = {
       return str
         .toLowerCase()
         .replace(/\s+/g, '_')  // Replace spaces with underscores
-        .replace(/[^a-z0-9_.]/g, ''); // Remove invalid characters
+        .replace(/[^a-z0-9_]/g, ''); // Remove invalid characters (keeping underscores only)
     };
 
     // Support both old and new signatures: