ci: run ClusterFuzzLite in batch mode

[marten-seemann]

Add ClusterFuzzLite batch fuzzing workflow to CI

Adds clusterfuzz-lite-batch.yml, a GitHub Actions workflow that builds Go fuzzers with address sanitizer and runs them in batch mode for 300 seconds. The workflow triggers on a cron schedule every 6 hours and on pull requests, emits SARIF output, and syncs artifacts to a configured storage repository via secrets.

^{Macroscope summarized 12bd7e0. (Automatic summaries will resume when PR exits draft mode or review begins).}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.55%. Comparing base (c350ec8) to head (dbe462f).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #86   +/-   ##
=======================================
  Coverage   93.55%   93.55%           
=======================================
  Files           4        4           
  Lines         186      186           
=======================================
  Hits          174      174           
  Misses          6        6           
  Partials        6        6           

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[codspeed-hq]

Merging this PR will not alter performance

✅ 4 untouched benchmarks

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_{Comparing clusterfuzz-lite-batch (dbe462f) with master (c350ec8)}