ci(release): run release pipeline from main with auto version tag

[Lythaeon]

Summary

• bump package version from 0.1.0 to 0.2.0
• update release workflow trigger to push on main only
• derive release tag automatically from Cargo.toml version (v<version>)
• skip release jobs when the resolved tag already exists
• build binaries from the merged main commit and attach them to the resolved release tag

Release CI Behavior Changes

• release workflow no longer runs on PRs or tag pushes
• release workflow runs only when commits are merged/pushed to main
• GitHub release is created at the merge commit with artifacts attached

Validation

• cargo make format-check
• cargo make test
• cargo make clippy