Add MetEngine smart money analytics

[vrajdesai78]

• Add 27 MetEngine smart money analytics commands (market discovery, intelligence,
  trades, wallet analytics) powered by x402 pay-per-request on Solana Mainnet
• Accept Polymarket URLs, slugs, or raw condition IDs for market-specific commands
  (resolves via Gamma SDK)
• Add x402 HTTP client with FreeClient (health/pricing) and PaidClient (Solana-signed
  paid endpoints)

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Note

Medium Risk
Introduces paid request signing and a large new dependency surface (Solana/x402/reqwest middleware), which can impact build size and runtime networking/payment behavior, but is largely additive and isolated to the new metengine path.

Overview
Adds a new metengine command group that exposes a broad set of smart-money analytics endpoints (market discovery, intelligence/trades, and wallet analytics), including market identifier resolution from condition ID, Polymarket URL, or slug (slug resolved via Gamma).

Introduces an x402-enabled HTTP layer with FreeClient for unauthenticated endpoints and PaidClient that auto-handles HTTP 402 payment challenges by signing Solana-mainnet USDC payments; wires in --solana-key plus METENGINE_SOLANA_KEY/config-file fallback for key resolution.

Updates docs and dependencies to support the new flow (adds reqwest/reqwest-middleware, Solana + x402-* crates, and relaxes alloy version constraint to <1.7).

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