Expand scientific codec validation and perf gates

[bbopen]

Expand scientific codec validation and performance gates so the 0.5.0 data-plane work is backed by real transport and payload-scale coverage.

Acceptance Criteria

• targeted tests cover large scientific payloads and the relevant transport paths
• perf-budget or payload-scale checks exist where transport behavior matters
• release gating includes the relevant scientific suites for the new data-plane work