Warning: This build has drifted.
The coverage report for this pull request build may be inaccurate because its base commit is no longer the HEAD of its target branch.
This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

    • Learn more: For more information on this, see Tracking coverage changes for pull request builds.
    • Fix now: For a quick fix, rebase this PR at GitHub. Your next report should be accurate.
    • Prevent going forward: To avoid this issue with future PRs, see these Recommended CI Configurations.

perf: replace put_in/Access.key with direct put_at_path recursion

copy_fields and apply_kv_instruction were doing
`put_in(acc, Enum.map(to_path, &Access.key(&1, %{})), value)` on every
event, which allocates one closure per path segment plus an intermediate
list. The new put_at_path/3 recurses directly over the parsed string
list (mirroring drop_field_at/2), eliminating those allocations on the
ingest hot path.

Benchmark (3s/2s, MIX_ENV=test): copy_fields parsed median drops from
~50μs to ~45μs per event (~10%) with no behavior change.