chore(release): 0.9.0

[stormer78]

Cuts 0.9.0, releasing the two additions merged in #24.

Changes

• Cargo.toml: 0.8.0 → 0.9.0
• CHANGELOG.md: the [Unreleased] content moves under ## [0.9.0] - 2026-09-09,
  with [Unreleased] left in place and empty for the next cycle

Nothing else. No code changes in this PR.

Why minor, not major

Both shipped items are additive — with_credential_status / set_credential_status
are new methods, and PartialEq (with Eq) on DTGCredentialType is a new trait
impl. No signature changed, and nothing changes on the wire for a credential that
does not use them. The last two releases were feat! majors; this one is not.

Contents of 0.9.0

• credentialStatus can be set on a credential being built. Modelled since 0.7.0,
  but only so an entry already on the wire survived a round trip without changing the
  digest; a credential built by a new_* constructor had no way to acquire one short
  of credential_mut. CONDITIONAL on a VDC rather than required — hence a setter, not
  a constructor parameter. Nothing here resolves the entry; revocation remains a live
  lookup the caller performs.
• PartialEq on DTGCredentialType, so consumers can assert by equality rather
  than by pattern.

Tagging

v0.9.0 once this merges. The publish workflow is tag-driven and no-ops cleanly if
the version is already on crates.io (#19).

Note

Trusted Publishing may still be unconfigured on crates.io — as of #19 it was, and
the first real release through the workflow will fail at the auth step until it is
set up. That is the correct failure, and the workflow header says how to fix it.

Verification

cargo test (121 passing), cargo clippy --all-targets, cargo fmt --check, and
cargo package --list against a clean tree all pass locally.