[cjohnhanson]

Releases 0.3.0. This is a minor release because it adds public library API.

• Adds Repo::keyed_batch(key) and KeyedBatch::upsert(NoteRecord) for loading large sets of notes by a frontmatter key field (feat: keyed upsert for large loads #33). Each upsert returns Created, Updated, Unchanged, or Conflict.
• Changes note create to list the store once per note and limit slugs to 100 bytes.
• Updates the version from 0.2.5 to 0.3.0 in Cargo.toml and Cargo.lock.
• Updates the README's .deb download URL and filename to v0.3.0.
• Updates rustls to 0.23.45 for RUSTSEC-2026-0285 and faster-hex to 0.10.1 for RUSTSEC-2026-0306 in Cargo.lock.