chore(release): prepare 2.3.2

[FlorentinDUBOIS]

Problem

The listener, certificate-state, activation rollback and cluster-answer validation fixes merged after 2.3.1 need a publishable Sōzu release. This change prepares 2.3.2 without changing runtime code.

Change

• move the complete unreleased notes into the 2.3.2 section dated 2026-10-15;
• keep all six package versions in lockstep at 2.3.2;
• update the root sozu-command-lib and sozu-lib requirements to ^2.3.2;
• update the RPM version;
• refresh the root and fuzz lockfiles through Cargo.

The release notes explicitly disclose that the new public ConfigState::certificate_metadata field breaks downstream exhaustive Rust struct literals. The command protobuf remains unchanged, and old JSON without the sidecar remains readable.

Validation

• cargo +nightly fmt --all -- --check
• cargo metadata --locked --offline --format-version 1
• cargo metadata --manifest-path fuzz/Cargo.toml --locked --offline --format-version 1
• independent frozen-diff review: no blocking finding, lockfile changes limited to local package versions

The complete GitHub Actions matrix and the release runtime qualification from published 2.3.1 remain required before merge and publication.

[FlorentinDUBOIS]

Please also hold 2.3.2 for #1899 (optional probe port on HealthCheckConfig, tag 9), targeted at this release.

[FlorentinDUBOIS]

Replaced by #1900, rebuilt from the final main that includes PRs #1891–#1899.