chore: prepare v0.1.3 release

[danielsuit]

Summary

• bump the Rust workspace and lockfile to v0.1.3
• move the current changelog entries into the v0.1.3 section dated 2026-09-04
• advance changelog comparison links for the next development cycle

Verification

• python3 scripts/check-release-version.py --tag v0.1.3
• cargo fmt --all -- --check
• cargo clippy --locked --workspace --all-targets -- -D warnings
• cargo test --locked --workspace
• cargo +1.89.0 check --locked --workspace

After merge, tag the merge commit as v0.1.3 to publish all four release archives, checksums, and Sigstore bundles.