fix(kalshi): remove obsolete integer market fields

[AnayGarodia]

Summary

• remove market-level cent price and integer volume/open-interest fields that Kalshi no longer returns
• normalize and sort current market responses exclusively from the dollar/fixed-point fields
• update the Kalshi normalizer fixture and remove the obsolete cent-price fallback test

Verification

• npm test --workspace=pmxt-core -- --runInBand test/normalizers/exchange-normalizers.test.ts (149 passed)
• npm run build --workspace=pmxt-core
• core portion of npm test (51 suites, 821 tests passed; the later Python SDK phase cannot collect in a fresh checkout because the generated pmxt_internal package and eth_account are unavailable)

Resolves #1748

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