Correct the published metadata

Adds library_name to the model card, and pipeline_tag where it was missing.
Brings the config and card licenses into agreement, and repairs the variant
declarations that did not match the files actually published here.

README.md

@@ -1,5 +1,5 @@
 ---
-license: apache-2.0
+license: gemma
 pipeline_tag: text-generation
 tags:
 - google
@@ -8,6 +8,7 @@ tags:
 - edge
 base_model:
 - google/gemma-4-E2B
+library_name: executorch
 ---
 
 # Introduction