Harden GitHub release creation for idempotent reruns

[Madhan230205]

Overview

GitHub release creation should be idempotent and robust across reruns and minor CLI behavior differences.

User Story

As a maintainer
I want release creation to be resilient and rerunnable
So that tagged releases do not require manual intervention after failures.

Context

• Current workflow creates release and skips if already exists.
• Pain point: reruns may not update/re-upload assets cleanly.
• Success metric: release pipeline succeeds on first run and reruns with no manual fixes.

Acceptance Criteria

• New tag creates release with generated notes + intro text.
• Existing release path uploads artifacts with overwrite/clobber behavior.
• Logs clearly show whether release was created or updated.
• Release step remains compatible with default ubuntu-latest gh CLI.

Technical Requirements

• Technology/framework: GitHub Actions + GitHub CLI
• Security: use GITHUB_TOKEN with contents:write only
• Performance: no major runtime increase

Definition of Done

• Workflow updated
• Validated with one new tag and one rerun scenario
• Docs updated in contribute.md

Estimated Effort

1 day