chore(release): prepare for release 18.13.0-beta.4

[ellie]

Checks

• I am happy for maintainers to push small adjustments to this PR, to speed up the review cycle
• I have checked that there are no existing pull requests for the same thing

[greptile-apps]

Greptile Summary

Routine version bump across all workspace crates from 18.13.0-beta.3 to 18.13.0-beta.4. All internal dependency references and the lock file are consistently updated. No logic changes.

Important Files Changed

Filename	Overview
Cargo.toml	Workspace version bump from 18.13.0-beta.3 to 18.13.0-beta.4 across all internal crate dependencies.
Cargo.lock	Lock file updated to reflect new version for all atuin-* crates.
crates/atuin-client/Cargo.toml	Version bump of atuin-common dependency to 18.13.0-beta.4.
crates/atuin-daemon/Cargo.toml	Version bump of atuin-common dev-dependency to 18.13.0-beta.4.
crates/atuin-dotfiles/Cargo.toml	Version bump of atuin-common and atuin-client dependencies to 18.13.0-beta.4.
crates/atuin-history/Cargo.toml	Version bump of atuin-client dependency to 18.13.0-beta.4.
crates/atuin-kv/Cargo.toml	Version bump of atuin-client and atuin-common dependencies to 18.13.0-beta.4.
crates/atuin-scripts/Cargo.toml	Version bump of atuin-client and atuin-common dependencies to 18.13.0-beta.4.
crates/atuin-server-database/Cargo.toml	Version bump of atuin-common dependency to 18.13.0-beta.4.
crates/atuin-server-postgres/Cargo.toml	Version bump of atuin-common and atuin-server-database dependencies to 18.13.0-beta.4.
crates/atuin-server-sqlite/Cargo.toml	Version bump of atuin-common and atuin-server-database dependencies to 18.13.0-beta.4.
crates/atuin/Cargo.toml	Version bump of atuin-ai, atuin-client, atuin-daemon, and atuin-hex dependencies to 18.13.0-beta.4.

_{Last reviewed commit: 8da6336}