Add codecov.yml with a 1% coverage threshold

[wbarnha]

Description

The repo has no Codecov config, so Codecov applies its default project status — target: auto, threshold: 0% — which fails the codecov/project check on any coverage decrease at all. In practice the drops are sub-0.1% jitter from async/threaded lines being counted slightly differently between runs (not real regressions), and they've been forcing admin-merges on otherwise-green PRs.

This adds a root codecov.yml giving project and patch a 1% threshold — enough slack to absorb the noise while still flagging a genuine coverage regression — and disables the per-PR Codecov comment (the status checks already carry the signal).

coverage:
  status:
    project:
      default:
        target: auto
        threshold: 1%
    patch:
      default:
        target: auto
        threshold: 1%
comment: false

Notes:

• Repo-wide policy change: it applies to all PRs once merged (it does not retroactively re-flip an already-run check; a re-run picks it up).
• Validated as well-formed YAML with the standard Codecov schema.

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Generated by Claude Code