v0.3.0

What's Changed

• Added rerun-safe release handling: existing releases can now be updated instead of always causing duplicate-release failures.
• Added configurable existing_release_behavior support with options to update drafts, fail, or update any existing release.
• Added secret redaction before sending commit data or GitHub-generated notes to OpenAI, with warnings when possible secrets are detected.
• Added diagnostic outputs for previous_tag, commit_count, prompt_char_count, used_batching, and redaction_count.
• Improved documentation and repository guidance.