feat: add helpers to fetch all market pages

[fatihv]

Summary

This PR adds four convenience methods to ClobClient:

• getAllMarkets
• getAllSimplifiedMarkets
• getAllSamplingMarkets
• getAllSamplingSimplifiedMarkets

Each helper iterates through the paginated CLOB API using next_cursor and
END_CURSOR, aggregating data from all pages into a single array.

Motivation

Currently, getMarkets, getSimplifiedMarkets, getSamplingMarkets and
getSamplingSimplifiedMarkets only return a single page of results. Client
code has to implement pagination manually. These helpers provide an ergonomic
way to fetch all markets without changing the existing API surface.

Implementation details

• Reuses existing single-page methods and the existing INITIAL_CURSOR /
  END_CURSOR constants.
• Loops until next_cursor === END_CURSOR and concatenates response.data.
• No breaking changes, the original methods are kept as-is.

---

Note

Adds four ClobClient helpers to iterate paginated markets and return aggregated results.

• Client (src/client.ts):
  • New pagination helpers:
    • getAllMarkets(next_cursor?): loops via next_cursor until END_CURSOR, aggregates response.data.
    • getAllSimplifiedMarkets(next_cursor?): same for simplified markets.
    • getAllSamplingMarkets(next_cursor?): same for sampling markets.
    • getAllSamplingSimplifiedMarkets(next_cursor?): same for sampling simplified markets.
  • Reuses existing single-page methods and INITIAL_CURSOR / END_CURSOR.

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