v0.1.6: Release Readiness Hardening

v0.1.6: Release Readiness Hardening

v0.1.6 is a release-readiness hardening update for the GQL mutable projection
stack. It clears the final pg17 release gate after the dependency refresh,
clippy cleanup, transaction-delta rollback fixes, and persisted metadata
serialization migration.

Highlights

• Moved persisted .pggraph metadata sections from bincode 1.3.3 to
  bincode 2.0.1 with serde support.
• Kept the .pggraph artifact format at version 2 and made metadata decoding
  reject trailing bytes instead of accepting partially consumed payloads.
• Skipped the published bincode 3.0.0 crate in dependency freshness checks
  because that release contains a top-level compile error.
• Fixed dirty transaction overlays so pending trigger sync rows are not applied
  into backend-local base projection state while transaction-local deltas are
  still uncommitted.
• Tightened the build-lock regression fixture so the concurrent slow-build path
  uses manual sync mode and does not trip trigger-sync behavior unrelated to
  the advisory-lock check.
• Cleared clippy blockers in GQL wildcard expansion, join binding, path-variable
  binding, and SQL admin single-row handling without broad lint suppressions.
• Documented the deferred nixpkgs and rust-overlay lock refresh as a
  Nix-environment follow-up rather than a release blocker.

Upgrade Note

`.pggraph` artifacts written before `v0.1.6` must be regenerated with `SELECT graph.build();` after upgrading. These files are derived artifacts, not the source of truth; PostgreSQL source tables remain authoritative.

This release intentionally chooses regeneration over compatibility shims for
old bincode metadata payloads. Future artifact tooling should move variable
metadata sections toward a pgGraph-owned binary encoding so artifact
compatibility is no longer tied to serializer crate behavior.

Validation

The full post-bincode pg17 release gate passed:

PG_VERSION_FEATURE=pg17 ./tests/heavy/run_release_gate.sh

That gate includes fmt, clippy, docs, unit tests, pgrx SQL tests, cargo-deny,
fuzz binary checks, package validation, fresh install smoke, metadata audit,
SQLSTATE/ACL boundary tests, backup/restore, advisory-lock regressions,
concurrency, synthetic smoke, rebuilt playground fixtures, pgbench sync stress,
and GQL transaction lifecycle and race scripts.