ts-sdk: coerce numeric inputs to bigint in id-like constructors

[Ludv1gL]

Description of Changes

The wrapper constructors for Identity, ConnectionId, Timestamp, TimeDuration, and Uuid all claim to take bigint (or string | bigint for Identity), but real-world callers can end up passing a number whenever data round-trips through JSON in caller-side code — JSON.parse has no way to produce a bigint, so a u128/u256 that goes through any JSON pipeline (custom state caches, hand-rolled HTTP clients, codegen drift, etc.) comes back as a lossy number.

The TS SDK itself does not do this — its normal flow is WebSocket BSATN, which is bigint-safe end-to-end. The fix is a defensive guard at the type boundary so that if something hands the SDK a number, the failure is graceful rather than a cryptic late crash.

Before this patch the constructors stored that number verbatim into a field typed as bigint. The failure then manifested several layers later in BSATN serialization, e.g. inside BinaryWriter.writeU256:

TypeError: Cannot mix BigInt and other types, use explicit conversions
    at BinaryWriter.writeU256 (binary_writer.ts:171:21)

with no indication of which call site was at fault.

Fix

Wrap the non-string branch of each constructor in BigInt(...):

Class	File	Behavior on number input — before	after
Identity	lib/identity.ts	silent corruption → late crash in writeU256	coerced to bigint
ConnectionId	lib/connection_id.ts	silent corruption → late crash in writeU128	coerced to bigint
Timestamp	lib/timestamp.ts	silent corruption → mix error in arithmetic / toDate()	coerced to bigint
TimeDuration	lib/time_duration.ts	silent corruption → mix error in arithmetic	coerced to bigint
Uuid	lib/uuid.ts	cryptic Cannot mix BigInt and other types from range check	range check passes / fails cleanly

• bigint inputs are returned unchanged (BigInt(123n) === 123n).
• number inputs are coerced cleanly. Precision was already lost upstream by whatever produced the number — this just stops the secondary crash.
• undefined / objects throw a clear TypeError immediately at the constructor, rather than several frames deep in serialization.

No public type signatures change; strict-TS callers compile-check exactly as before.

Tests

Added crates/bindings-typescript/tests/id_ctor_coercion.test.ts pinning the new behavior across all five classes (9 cases): bigint pass-through, number coercion, hex-string parsing for Identity, range check preservation for Uuid, and clear errors on undefined.

Full test suite (pnpm run test) — 191 passed, 0 failed.
pnpm run lint — clean.
pnpm run build:types — clean.

API and ABI breaking changes

None. Public type signatures unchanged. Behavior is strictly more permissive (previously-failing inputs now succeed or throw earlier with a clearer error).

Expected complexity level and risk

1 — narrow defensive change, six small constructors, isolated tests.