spec: ratify RFC-001 (issue #56)

[trendvidia]

Summary

Ratifies RFC-001 — Protowire Schema Extensions (S3 closer; #56): header status Draft → Ratified (2026-07-16), authors set, and §13 rows 13/14 now cite their freshly filed tracking issues (#111 sensitivity-class taxonomy, #112 @encrypted(key_ref)).

Acceptance criteria (#56)

• Approving review from spec governance — granted in-session by the maintainer (single-maintainer governance; S1/S2/S3 precedent), recorded in the deps(go): bump the go-minor-and-patch group across 1 directory with 3 updates #2 resolution record (second commit).
• All open questions resolved or tracked: §13 rows 2–7 resolved in S1 (PRs spec: pin validation report wire shape in report.proto (RFC-001 §7) #94–spec: finalize Literal carrier shape (RFC-001 §8.1) #99); source grammar/pxf: reject schemas using PXF-reserved names (null/true/false) #15, secrets/deps(vscode): bump the vscode-minor-and-patch group in /editors/vscode with 2 updates #21, descriptor_path/feat(pxq): in-document @proto as a schema source #35 resolved in S2 (PRs spec: ratify canonical descriptor_path grammar (RFC-001 §8.3.1) #106–spec: pin message-literal source grammar (RFC-001 §5.1) #108); engine-expression scope/docs(pxf): @table streaming-consumption note (v0.74 prep) #22 and pxf dual-emission/release: cut v0.74.0 #23 resolved in S3 (PRs spec: pin engine-expression grammar — annotation-only v1.2 (RFC-001 §5.1/§8.1) #109, spec: no pxf.* dual-emission — @required/@default are carrier-only (RFC-001 §8.5) #110). Remaining rows all tracked: Container-shaped type aliases (deferred to v1.3+) #59, protovalidate migration story #66–Upstream buf/protocompile compatibility strategy #69, Stream-level validation invariants (deferred from §6.6) #103, Sensitivity-class taxonomy — @sensitive(class: ...) (deferred from §6.7) #111, Schema-level encryption / key-reference annotation — @encrypted(key_ref) (deferred from §6.7) #112.
• No locked decision blocks an existing port's roadmap: all v1.2 surface is strictly additive; per-port adoption is M9+ gated on the conformance corpus (Conformance test corpus expansion #68). release: cut v0.74.0 #23's carrier-only decision constrains migration ordering (runtimes before schemas), not any roadmap.

Closes #56. Tracked by #55. Next and final S3 item: #57 (generate + submit IETF -01).