Fix Codecov v7 coverage file input

[konard]

Fixes #34.

Summary

• Keep the release workflow on codecov/codecov-action@v7.
• Complete the v4-to-v7 migration by renaming the deprecated singular file input to v7's files input.
• Strengthen the workflow regression test to require files and reject the legacy singular input.
• Add a changelog fragment and remove the autogenerated branch placeholder.

Root cause and reproduction

The Codecov action tag had already been upgraded to v7 by #36, but its configuration still used the v4-era file input. The focused regression test reproduces the partial migration by failing with:

assert "files: ${{ steps.python_layout.outputs.root }}/coverage.xml" in upload_step

This means a straight major-version bump could silently stop selecting the generated coverage.xml report.

Verification

• .venv/bin/python -m pytest tests/test_workflows.py::test_release_workflow_gates_codecov_upload_on_token -q
• .venv/bin/python -m pytest --cov=src --cov-report=term (45 passed, 100% package coverage)
• .venv/bin/ruff check .
• .venv/bin/ruff format --check .
• .venv/bin/mypy src/
• .venv/bin/python scripts/check_file_size.py
• .venv/bin/pre-commit run check-yaml --files .github/workflows/release.yml
• git diff --check

mypy passed with the repository's existing Python 3.9 support and strict_concatenate deprecation warnings.

[konard]

Working session summary

Implemented and pushed the Codecov v7 migration fix.

• Changed the legacy file input to v7’s files input.
• Added regression coverage rejecting the legacy input.
• Added a changelog fragment.
• Merged current main.
• Updated PR title/description and marked it ready.
• Local checks pass: 45 tests, 100% coverage, Ruff, mypy, YAML, and file-size checks.
• Worktree is clean.

PR: #38

GitHub Actions run is created but remains pending with zero jobs scheduled: https://github.com/link-foundation/python-ai-driven-development-pipeline-template/actions/runs/29958895118

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[konard]

🤖 Solution Draft Log

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💰 Cost estimation:

• Model: GPT-5.6 Sol
• Provider: OpenAI
• Public pricing estimate: $2.590481

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• 73.9K / 200K (37%) input tokens, 7.0K / 128K (5%) output tokens

Total: (73.9K + 1.5M cached) input tokens, 7.0K output tokens, $2.590481 cost

🤖 Models used:

• Tool: OpenAI Codex
• Requested: gpt-5.6-sol
• Thinking level: off (disabled)
• Model: GPT-5.6 Sol (gpt-5.6-sol)

📎 Log file uploaded as Gist (1035KB)

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[konard]

🎉 Auto-merged

This pull request has been automatically merged by hive-mind.

• All CI checks have passed

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Auto-merged by hive-mind with --auto-merge flag