codeSplitters: redact query strings in Workers Logs #553

Found while doing #516 (PR #552). The live codesplitters Worker has observability.redact_query_string: false, so anything passed in a query string (OAuth codes, ?confirm= handles, any token someone puts in a URL) is kept in Workers Logs for 7 days. Set redaction on in rustybuns.config.ts / Alchemy's observability settings, then update the 'Request logs' row on #/privacy to say query strings are dropped.