feat(extensions): add PGMQ native and WASIX qualification

[f0rr0]

Summary

• pin PGMQ 1.12.0 to exact upstream commit 08ace4087dbf00e51704c5a3d9df2e15fd566127 with its PostgreSQL license bytes
• register PGMQ as a SQL-only qualification candidate for native desktop and WASIX portable targets
• add queue lifecycle smoke coverage and target-scoped candidate/legal expectations
• support extensions whose PGXS root lives below the upstream checkout, then regenerate catalogs, build plans, graph fixtures, evidence, and semantic fingerprints

Why

PGMQ's PostgreSQL extension lives in the upstream pgmq-extension/ subdirectory. Oliphaunt previously assumed an external extension's PGXS root was the checkout root, so the catalog and build plan needed an explicit nested import path.

The extension is deliberately fail-closed as a deferred candidate. It remains outside public release and SDK catalogs until exact-commit native/WASIX package and lifecycle evidence is produced.

Impact

Native desktop and WASIX CI matrices now select PGMQ for qualification. Mobile remains unsupported, and there is no public package or release product exposure in this change.

Validation

• tools/dev/bun.sh tools/release/release-check.mjs — 1,587 passed, 15 platform-specific skips, 0 failures
• cargo test -p xtask extension_catalog — 6 passed
• extension model, tree, source-pin, legal, graph, and WASIX asset fingerprint checks passed
• PostgreSQL 18 native lifecycle smoke passed for create/send/read/archive/drop plus dump/restore