refactor(node): use raw Taffy node IDs

[hyfdev]

Summary

• expose each public NodeId as the raw Taffy u64 bigint with a compile-time TypeScript brand
• remove tree tokens, creation serials, owner and liveness registries, and their public error codes
• make tree and lifetime correctness a caller precondition while retaining bigint/u64 input checks
• document and regression-test native invalid-key panic containment
• update and re-vouch the affected PCR decisions and public documentation

Contract

A NodeId is supported only while its node is live and only with the TaffyTree that returned it. Independent trees may issue equal raw values. Forged, foreign, and stale in-range values are unsupported and have no stable error classification.

Verification

• pnpm vp run check
• pnpm vp run check:wasm
• git diff --check

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[hyfdev]

Adversarial review

Reviewed the change by trying to break these assumptions:

• public values are bit-for-bit the raw Taffy u64 NodeId
• every caller-supplied NodeId reaches the bigint/u64 representation check
• context and measure maps remain consistent with the receiving tree
• every native tree access stays inside the panic-containment boundary
• removed tests cover only the retired owner/liveness contract
• Native, Wasm, generated declarations, public docs, and PCR state agree

Findings fixed during the review:

1. Added one direct public-versus-native raw-value test and one multi-NodeId representation/atomicity test without restoring per-method matrices.
2. Removed remaining claims about stable NodeId codes and owner/liveness validation from the binding and Wasm records.
3. Clarified that NodeId representation failures use TypeError while other numeric range failures use RangeError.
4. Kept concrete foreign-ID behavior out of regression tests because it is explicitly unsupported.

The project owner classified this PR as a normal refactor rather than a breaking release change, so its squash title remains refactor(node): use raw Taffy node IDs.

No unresolved implementation findings remain. Local pnpm vp run check and pnpm vp run check:wasm pass. GitHub CI is 6/6 green across Ubuntu, Windows, Wasm, Node, Rust, and the PR-title check.