Fix missing timestamps and add backfill script

Signed-off-by: Lukasz Gryglicki <[email protected]>

Assisted by [OpenAI](https://platform.openai.com/)

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Author: lukaszgryglicki

.gitignore

@@ -261,3 +261,4 @@ out.json
 body.json
 
 cla-backend-go/signatures_timestamp_backfill
+cla-backend-go/backfill-fallback-commands-cla*.sh