Bump version from 0.29.0 to 0.30.0

[avrabe]

No description provided.

[avrabe]

Superseded by #117, which carries this exact change plus the two things that make it pass CI.

Closing rather than fixing in place, because the branch would need all three anyway.

Why this one goes red

The bump is correct as far as it goes — it just cannot stand alone. Cargo.toml names the version in two places:

[workspace.package]
version = "0.30.0"          # this PR changes this one

[workspace.dependencies]
varve-core = { path = "crates/varve-core", version = "0.29.0" }   # and not this one

With those disagreeing, cargo update -w refuses outright:

error: failed to select a version for the requirement `varve-core = "^0.29.0"`
candidate versions found which didn't match: 0.30.0

And because Cargo.lock still records 0.29.0, every job that builds with --locked fails with "the lock file needs to be updated but --locked was passed" — which is the five failures here.

Not an obvious trap: I hit the identical one cutting v0.29.0, and again last week when adding varve-producer to the workspace. A local cargo test updates the lockfile silently, so only CI ever notices.

What #117 does instead

• both version sites in Cargo.toml
• Cargo.lock refreshed, so cargo build --workspace --locked is clean
• the v0.30.0 release notes

21/21 green there.