fix: support Bombadil snapshots in Boa

[0thernet]

Summary

• makes named snapshot validation portable to Bombadil 0.7.2's Boa runtime without TextEncoder
• keeps the snapshot helper in a driver-neutral private package module
• adds a real packaged Boa smoke and freezes the package/release boundary for 0.7.10

Evidence

• canonical Bun 1.3.14 full check passed under the exclusive repository scheduler
• typecheck, immutable release-history checks, canonical build, package smoke, 340 source tests, lint, Todo production/Direct boundaries, and React Native iOS/Android/Web verification passed
• packaged Boa 0.7.2 smoke passed with TextEncoder absent, a raw lone-surrogate fallback, and the canonical JSON-boundary representation
• package inventory: 59 files, 211,934 packed bytes, 999,525 unpacked bytes
• exact base: 2d702f2
• exact head: 6d6292d