feat(interface): make native continuation retry-safe

[drewstone]

Summary

• bind same-session continuation to the exact new user turn
• add one atomic provider operation with runtime-checked results and current run coordinates
• prove replay returns the original result, changed input conflicts, and transport failures remain safe to retry

Proof

• pnpm build
• pnpm check-types
• pnpm test: 1,030 tests passed
• pnpm check:package-artifacts: 9 packages, 19 exports, 38 export targets
• pnpm check:control-artifacts: 7 packed test files, 108 tests passed