relay: decide the 1.0 standards roster; feature-freeze or remove standards without committed adopters

[jeremi]

Found during the 2026-07-07 architecture audit.

Context

Relay compiles seven-plus API standards into one binary: OGC API Features, OGC EDR, OGC Records, SP DCI, SDMX aggregates, DCAT-AP + SHACL, RFC 9727 API catalog, attribute release, plus CSV/Parquet/XLSX output. 93 route registrations, 124 feature gates. Compile-feature defaults are already lean (good); the issue is what 1.0 commits to: every shipped standard is contract forever, and the feature x runtime-config matrix is the main driver of config/validate.rs (5,031 lines) and the 42.5k-line integration-test mass.

Scope

For each standard: does it have a committed adopter for 1.0?

• Yes: keep, in the stability promise.
• No: mark experimental (explicitly outside 1.0 stability promises) or remove.

Also worth folding in: attribute-release CEL expressions are currently evaluated by synthesizing single-field SP DCI mapping documents and reading the output field back (src/attribute_release/mod.rs:12-19). If attribute release stays in the roster, consider evaluating CEL directly instead of through the mapping-document contortion.

Acceptance

• Documented standards roster with stability tier per standard.
• Non-roster standards feature-frozen or removed; docs and release notes state the tiers.