Release v0.2.1

Patch release: aligns Cargo.toml crate version with git tag so mqtt-recorder --version reports correctly.

Changes:

• Bump crate version from 0.1.0 → 0.2.1
• No functional changes — all v0.2.0 features intact

Full Changelog: v0.2.0...v0.2.1

What's Changed

• chore: bump crate version to 0.2.0 to match release tag by @briananderson1222 in #3
• chore: release v0.2.1 by @briananderson1222 in #4

Full Changelog: v0.2.0...v0.2.1