Add script to draft release notes from GitHub API

[tautschnig]

Add scripts/draft_release_notes.py, which calls the GitHub release-notes generation endpoint (via gh) to produce a PR list in the same format as the existing CHANGELOG file. It also prepends a heuristic draft summary paragraph that highlights user-visible features and counts bug fixes. The summary is marked with an HTML comment reminding the release manager to review and edit it before committing.

Usage: scripts/draft_release_notes.py cbmc-

Also add a link to the CHANGELOG file in the release body generated by the regular-release workflow, and update doc/ADR/release_process.md to document the new script.

Fixes: #7907

• Each commit message has a non-empty body, explaining why the change was made.
• n/a Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• n/a The feature or user visible behaviour I have added or modified has been documented in the User Guide in doc/cprover-manual/
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• n/a My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• n/a White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[Copilot]

Pull request overview

Adds automation to draft CBMC release notes from GitHub-generated release notes, and updates the release workflow/docs to integrate the changelog into the release process.

Changes:

• Add scripts/draft_release_notes.py to generate a draft CHANGELOG entry (including a heuristic summary) using the GitHub release-notes API via gh.
• Document the new changelog drafting step in doc/ADR/release_process.md.
• Add a CHANGELOG link to the release body in .github/workflows/regular-release.yaml.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
scripts/draft_release_notes.py	New script to generate draft release notes/CHANGELOG entry from GitHub API output.
doc/ADR/release_process.md	Documents the changelog/release-notes drafting step for release managers.
.github/workflows/regular-release.yaml	Adds a CHANGELOG reference to the auto-created GitHub release body.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.49%. Comparing base (0656298) to head (08e4d46).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #8934   +/-   ##
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  Coverage    80.49%   80.49%           
========================================
  Files         1704     1704           
  Lines       188805   188805           
  Branches        73       73           
========================================
+ Hits        151983   151986    +3     
+ Misses       36822    36819    -3     

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