fix(client): split rejected RPC batches

[cesarenaldi]

Summary

• Batch setup approval eth_call checks through the Python JSON-RPC client.
• Retry rejected 5xx JSON-RPC batches by recursively splitting them down to single calls.
• Preserve result ordering across split retries for approval resolution.

Fixes #116

Verification

• uv run ruff format --check src/polymarket/_internal/eoa/rpc.py src/polymarket/_internal/actions/relayer/approvals.py tests/unit/_relayer_helpers.py tests/unit/test_eoa_rpc.py tests/unit/test_eoa_broadcast.py
• uv run ruff check src/polymarket/_internal/eoa/rpc.py src/polymarket/_internal/actions/relayer/approvals.py tests/unit/_relayer_helpers.py tests/unit/test_eoa_rpc.py tests/unit/test_eoa_broadcast.py
• uv run pyright src/polymarket/_internal/eoa/rpc.py src/polymarket/_internal/actions/relayer/approvals.py tests/unit/_relayer_helpers.py tests/unit/test_eoa_rpc.py tests/unit/test_eoa_broadcast.py
• uv run pytest tests/unit

---

Note

Medium Risk
Changes RPC transport and approval-read paths used before submitting on-chain approvals; incorrect batch parsing or ordering could mis-detect missing approvals, though behavior is covered by new unit tests.

Overview
Adds eth_call_batch on async and sync JSON-RPC clients so multiple eth_calls go out in one HTTP JSON-RPC array, with shared parsing helpers extracted from single-call paths.

When a batch POST fails with a 5xx RequestRejectedError, the client recursively splits the batch (down to single calls) and merges results in original order; client errors below 500 are not retried via splitting.

Trading approval resolution (resolve_missing_trading_approval_calls / sync) now batches all ERC20 allowance and ERC1155 isApprovedForAll reads in one batch instead of awaiting each eth_call separately. Unit mocks and tests were updated for batch request bodies; new tests cover split-on-5xx ordering for async and sync clients.

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