wasm: add BIP39 passphrase support to make_default_account_privkey

[erubboli]

Fixes the Mojito mobile wallet blocker (High, CWE-325): the wasm API had no way to pass a BIP39 passphrase to key derivation.

Stacked on #2112 (supply-chain/lockfile context needed for cargo-deny/vet).

API shape

Chose the single-entry-point form over a new export:

make_default_account_privkey(mnemonic: &str, network: Network, passphrase: Option<String>)

• keeps one entry point (no API surface duplication), matching the desktop wallet's MasterKeyChain::mnemonic_to_root_key(mnemonic, Option<&str>) signature
• wasm-bindgen renders it as passphrase?: string | null in the generated TS bindings — an optional third argument, so all existing 2-argument JS callers keep working unchanged

Semantics

seed = PBKDF2-HMAC-SHA512(mnemonic, salt = "mnemonic" + passphrase, 2048 iterations, 64 bytes) via bip39's to_seed (which performs the required NFKD normalization) — same call pattern as Core desktop (to_seed(passphrase.unwrap_or(""))). None/undefined/null/"" are all byte-identical to the old behavior. Passphrase and seed are wrapped in Zeroizing (best-effort; see comment in code).

Backward compatibility (regression-tested)

Pinned vectors captured from the pre-change implementation and asserted in legacy_derivations_unchanged: empty-passphrase derivations on mainnet and testnet, plus receiving keys at index 0 and 1 for both networks. The existing JS predefined_address_test (2-argument call, pinned address) continues to pass unchanged.

Tests

• bip39_trezor_test_vectors — 5 official BIP39 Trezor vectors ("TREZOR" passphrase), cross-checked against an independent PBKDF2 implementation
• non_ascii_passphrase_normalization — NFKD normalization pinned with independently computed vectors (non-ASCII/Unicode-separator passphrases), the interop concern for arbitrary JS strings
• different_passphrases_produce_different_keys — same mnemonic, different passphrases → different extended keys and different receiving addresses
• wasm_matches_core_key_chain — acceptance gate: MasterKeyChain::mnemonic_to_root_key (Core desktop key-management) and the wasm export derive identical account keys and identical addresses for the same mnemonic + passphrase
• JS bindings: legacy call forms equivalence, passphrase reproducibility, distinctness (run via wasm-pack + node; all pass, including all pre-existing tests)

Call-path audit (requirement 5)

• make_receiving_address / make_change_address / make_receiving_address_public_key / make_change_address_public_key: consume the already-extended account key — no change needed ✅
• encode_witness / sign_message_for_spending: consume raw private keys derived downstream — no mnemonic involved ✅
• sign_challenge / verify_challenge: consume a private key / address, no mnemonic ✅
• Only remaining mnemonic→seed site in the workspace besides wasm-wrappers: wallet's MasterKeyChain::mnemonic_to_root_key, which already takes the passphrase (and is the interop reference for this PR) ✅

Versioning

This PR is version-neutral (no workspace/npm version change); the changelog entry lives under [Unreleased]. The version upgrade to 1.5.0 will be coordinated separately in a dedicated release PR. README documents the new parameter; generated WASM-API.md and wasm_wrappers.d.ts updated (passphrase?: string | null).

Compatibility note

Affected wallets: only wallets created from a mnemonic with a user passphrase (currently impossible via wasm — that's the bug). Legacy wallets (no passphrase) must keep deriving with None/undefined; mixing them up produces different keys. Migration for the mobile wallet: re-vendor the wasm package; for new wallets pass the user's passphrase; for existing (legacy) wallets pass nothing.

Verification

• full ./do_checks.sh green locally under the CI toolchain (1.92.0): fmt, cargo-deny, cargo-vet, clippy (all targets), codecheck, wasm-doc check
• cargo test --workspace (all 202 test binaries) green locally — includes the node-daemon / wallet-rpc-daemon RPC doc expect-tests
• cargo test -p wasm-wrappers: 7/7 pass; full JS bindings suite via wasm-pack build + node: all pass
• local AI code review (open-code-review CLI / glm-5.3-flash) run on the diff before pushing; all findings addressed (wallet dev-dep default features, non-ASCII normalization coverage, zeroization comment accuracy, strict equality in JS tests, plus small fixes landed in Fix remaining Dependabot alerts: hickory-proto (#62), rand (#54), lru (#44) #2112)

[github-actions]

✅ OpenCodeReview: Review complete: 0 finding(s) across 5 selected item(s).