docs: add conformance status badges

[zhongkechen]

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Issue Link, if available

N/A

Description

Adds README status badges for the core and OpenTelemetry conformance test workflows.

Demo/Screenshots

Not applicable. The change adds status badges to the README header.

Checklist

• I have filled out every section of the PR template
• I have thoroughly tested this change

Testing

Unit Tests

Not applicable for a documentation-only change.

Integration Tests

Not applicable for a documentation-only change.

Examples

Not applicable.

Validated with git diff --check and confirmed both workflow paths are active on main.

[github-actions]

Claude AI review

This PR adds two status badges to the README header for the "Core Conformance" (conformance-tests.yml) and "OpenTelemetry Conformance" (otel-conformance-tests.yml) workflows.

Verification performed:

• Confirmed both referenced workflow files exist at .github/workflows/conformance-tests.yml and .github/workflows/otel-conformance-tests.yml, and the badge URLs (actions/workflows/<file>/badge.svg) correctly match those filenames — so neither badge will 404.
• Both files are valid workflow definitions (name: Conformance Tests and name: OTel Conformance Tests).
• The added lines are well-formed Markdown and consistent in style with the existing badge rows.

No findings. The change is documentation-only, touches no SDK code, and introduces no correctness, API-compatibility, serialization, checkpoint/replay, lifecycle, concurrency, or logging concerns.

Residual test risk: None warranting tests — this is a README-only change. One minor cosmetic note (not blocking): both workflows trigger only on pull_request to main, so the rendered badges may display "no status" on the default branch until a qualifying run is associated with main; this does not affect link validity.

Reviewed commit 11b847a866ded2b13f31a3b1434669816555ad60. Workflow run

[github-actions]

Codex AI review

No actionable findings. Both badge workflow paths exist; residual risk is limited to live GitHub badge rendering, which was not exercised.

Reviewed commit 11b847a866ded2b13f31a3b1434669816555ad60. Workflow run