Pin-blocked conformance residues (#13 exit): name-option + thread-encoding xfails need wasmparser >= 0.255 #152

Narrow successor to #1 (closed not-planned: there is nothing to bump to), scoped to the four xfail entries that #13's closeout re-classified as wasmparser-pin-blocked, not shim gaps. The rejecting decoder is wasmparser 0.252 inside wasmtime-environ 47.0.3 — the error strings (`invalid leading byte`, `invalid boolean value`) do not occur in `crates/translator-shim` code.

The entries

• `binary/binary.json:1194`, `validation/attributes.json:30`, `validation/attributes.json:213` — the 0x2 leading byte for import/export name options is the 🔗 canonical-interface-names encoding (`canonversion` + split `versionsuffix`), which postdates wasmparser 0.252. See the forward note in contracts/embedder-api.md ("Forward note (wasmtime-bump era)").
• `binary/binary.json:962` — 🧵 thread built-in encodings, re-aritied in the wasmparser 0.253–0.255 window; dual-classed with the deferred-threads feature (memory64 + shared-everything threads: deferred feature tracking #12).

The 47-entry `trap-if-block-and-sync` class and the `during-sync-call-*` entries share the same pin root but are tracked under #12 (they are thread-feature tests regardless of the pin).

Exit

Bump the pin when a stable wasmtime-environ with wasmparser ≥ 0.255 ships (trigger: wasmtime 48; crates.io max stable was still 47.0.3 on 2026-08-17). Staging carried over from #1:

1. Before/after regression diff with the consumer corpus: `tools/smoke-c0` legs 3+4 stay 9/9 accepted, zero rejections.
2. Full conformance table compare; only the named pin classes may move.
3. Post-bump: add the optional `versionSuffix` field to plan import/export entries (contracts/embedder-api.md, version resolution).

Deliberately an attended task (docs/architecture.md §12: highest-churn-risk change in the repo).