Release RustQueue 0.8.3

[SamuelSupe]

Summary

• Replace full in-flight deadline scans with ordered indexes in durable Channels and TCP sessions.
• Preserve the v7 format and acknowledged-after-fsync PUB, FIN, and REQ contracts.
• Add an NSQ v1.3.0 performance-boundary comparison and update 0.8.3 release metadata.

Why

At high RDY and many active consumer connections, deadline expiry previously performed repeated full in-flight scans. NSQ uses a priority queue for this path; this release aligns RustQueue's scheduler shape without weakening its durability boundary.

Validation

• ./scripts/verify-release-version.sh 0.8.3
• FULL=1 K8S_ACCEPTANCE=0 FUZZ_SECONDS=1 ./scripts/release-gate.sh
  • format, all-feature check, full tests, Clippy, Console UI check/build, Helm lint/template, fuzz smoke, release image, Go/Python core and TLS compatibility

Kubernetes acceptance was not run because this release does not change Kubernetes behavior.