Add release body templating support

[anton-yurchenko]

Summary

• add BodyTemplate configuration and new GetBody helper
• wire up release body creation in main
• support templated release bodies in release package
• document BODY_TEMPLATE and show example usage
• test new body logic

Testing

• go test ./...

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https://chatgpt.com/codex/tasks/task_b_6841efe5834083318d93d43cd7d881ed

[Copilot]

Pull Request Overview

This PR adds release body templating support to allow users to customize release bodies using templates. Key changes include:

• Adding a new Body field in the Release struct and updating its handling in publishing logic.
• Implementing a GetBody helper in the configuration to parse a templated release body.
• Updating tests and documentation to include and verify templated release bodies.

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
release/release_test.go	Updated test cases with new Body field for release creation mocks.
release/release.go	Updated release publishing to use the new Body field.
release/modal.go	Extended the Release struct to include a Body field.
main.go	Integrated GetBody call to generate the release body before publishing.
docs/example.md	Added documentation example for using a release body template.
config_test.go	Added tests to verify the behavior of the GetBody helper function.
config.go	Added a BodyTemplate field and implemented the GetBody templating.
README.md	Documented the new BODY_TEMPLATE environment variable.