Add release notes for 3.7.0-rc1

[Copilot]

Purpose

Draft developer-facing release notes for the 3.7.0-rc1 release.

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Scope

Select one primary concern:

• Bug fix (behavior change)
• Refactor (no behavior change)
• Documentation update
• Formatting / code cleanup
• Dependency / build update
• New feature

If this PR includes multiple unrelated concerns, please split it before requesting review.

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Description

Problem

The 3.7.0-rc1 release did not yet have a changelog entry under doc/changelogs.

Solution

• Added doc/changelogs/3.7.0-rc1.md.
• Used comparison range 3.6.0...3.7.0-rc1.
• Organized developer-facing changes into release-note sections:
  • Breaking changes / upgrade notes
  • New features
  • Improvements
  • Fixes
  • CI / build
  • Full changelog

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Verification

Review the generated changelog for accuracy against the release comparison.

Steps:

1. Open doc/changelogs/3.7.0-rc1.md.
2. Confirm the comparison range is 3.6.0...3.7.0-rc1.
3. Spot-check listed PRs and commits against the GitHub release history.

Expected outcome:

The changelog accurately summarizes developer-facing changes for 3.7.0-rc1.

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Screenshots / Recordings (if applicable)

N/A — documentation-only change.

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Commit Convention

We recommend using conventional commit prefixes:

• fix: – Bug fixes (behavior change)
• feat: – New features
• refactor: – Code changes without behavior change
• docs: – Documentation updates
• chore: – Maintenance, tooling, or dependency updates
• test: – Test additions or modifications

Clear commit messages make reviews easier and history more meaningful.

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Checklist

• The PR is focused on a single concern
• Commit messages follow the recommended convention
• Tests added or updated (if applicable)
• Documentation updated (if applicable)
• No unrelated cleanup included
• All tests pass