Migrate CLOB order submission to SDK v2

[suhailkakar]

Note

Medium Risk
Updates trading and on-chain transaction paths (order submission, approvals, CTF ops) and introduces proxy-wallet transaction routing, which could affect signing/tx execution and user funds if misconfigured.

Overview
Migrates the CLI from polymarket-client-sdk to polymarket_client_sdk_v2 (plus updated alloy features/lockfile deps) and switches CLOB order submission for create-order/market-order to sign then submit via post_orders.

Reworks on-chain flows: adds shared Polygon contract address constants and a proxy helper to route transactions either directly or through the Polymarket proxy wallet factory, then updates approve and all ctf commands to use ABI-encoded calls and proxy-aware sending. User-facing docs/output are updated accordingly (USDC → pUSD, richer JSON error chains, approval output tweaks, and paginated earnings-markets output).

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