fix: omit user stream market filter for all markets

[cesarenaldi]

Summary

• Omit the user stream markets filter when subscribing to all markets
• Keep narrowed user stream subscriptions sending markets: [...]
• Add coverage for the broad user stream initial subscribe frame

Verification

• pnpm lint
• pnpm typecheck
• pnpm test:client

Notes

• This matches the Python SDK fix in fix: omit user stream market filter for all markets py-sdk#103.

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Note

Medium Risk
Changes live websocket subscription wire format for a common { topic: 'user' } path, which can affect real-time order/trade delivery; behavior is intentional and test-covered but touches trading-adjacent infrastructure.

Overview
Broad user websocket subscriptions no longer send a markets field on the initial subscribe frame when includeAllMarkets is true (buildUserSubscribeMessage in protocol.ts). Narrow subscriptions still include markets: [...]. This aligns with the Python SDK fix so all-market user streams can receive trade events (and related updates) that were previously filtered incorrectly.

Bindings: e6-scaled bigint string parsing is centralized as E6BigIntStringToDecimalStringSchema in shared.ts (RFQ schemas now import it). Order response empty-string amount normalization is renamed to OrderResponseAmountSchema with no behavior change.

Tests: Unit coverage for the all-markets subscribe frame; user subscription integration tests move into subscriptions.test.ts, including a metered test that asserts a trade event after a market order. Standalone user-subscriptions.test.ts is removed.

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