bump versions and add changelog for pr #49 and #50

[fabracht]

Summary

• This is a metadata-only catch-up PR. The actual code referenced in the CHANGELOG entry shipped via split licensing: apache-2.0 for core/agent/wasm, agpl for vault/cluster/cli #49 (license split + vault extraction into mqdb-vault) and include db_data in partition snapshot export/import #50 (db_data partition snapshot fix). This PR contains only Cargo.toml version edits, a CHANGELOG entry, regenerated lockfiles, and one drive-by fix for a pedantic clippy warning that pre-commit surfaced.
• Bumps crate versions and adds a single dated CHANGELOG entry covering the two functional PRs that have landed on main since v0.7.3. Decoupled from the functional PRs so versioning is clean and reviewable on its own.
• Drive-by fix: pedantic redundant_closure_for_method_calls warning at crates/mqdb-cluster/src/cluster/node_controller/db_ops.rs:2065, introduced by the diagnostic warn!() site added in include db_data in partition snapshot export/import #50. Replaced |s| s.role() with a direct method reference + top-level use crate::cluster::replication::ReplicaState.

Version map

Crate	From	To	Reason
mqdb-core	0.6.0	0.7.0	breaking: vault_keys module removed from public API
mqdb-agent	0.7.2	0.8.0	breaking: vault_ops module removed, MqdbAgent public fields dropped, vault handlers re-shaped around VaultBackend
mqdb-wasm	0.3.1	0.3.2	license flip only (Apache-2.0)
mqdb-vault	—	0.1.0	new crate (AGPL-3.0-only, publish = false)
mqdb-cluster	0.3.0	0.3.1	db_data partition snapshot fix + DbAccess integration (publish = false)
mqdb-cli	0.7.3	0.7.4	license gating + cluster vault admin routing (publish = false)

Downstream Cargo.toml version specifiers (mqdb-agent/Cargo.toml → mqdb-core, mqdb-vault/Cargo.toml → mqdb-agent + mqdb-core) updated in lockstep. Both Cargo.lock files (workspace + crates/mqdb-wasm/) regenerated.

Test plan

• cargo check --workspace --all-targets — clean
• cargo test --workspace --no-run — all test binaries build clean against the new version specifiers
• cargo make clippy (pedantic, all targets + wasm) — clean (fixed the redundant_closure_for_method_calls warning)
• cargo make format-check — clean
• Pre-commit hook ran format-check + clippy and passed on every commit