feat: add Router Core V3 to Base and Solana clients

[KillerQueen-Z]

Summary

• add a native Python Router Core V3 adapter pinned to commit d430804
• expose route(), smart_chat(), and smart_chat_completion() on Base/Solana sync and async clients
• support blockrun/auto, blockrun/eco, and blockrun/premium for chat, tool/agent, and streaming requests
• preserve full routing metadata and capability-safe transient fallback order
• use live model catalog pricing and chain-specific x402 minimums

Validation

• Router Core golden conformance across 14 task shapes and all four client variants
• 470 unit tests passed
• Ruff and package compilation/wheel build passed
• real paid E2E passed on Base and Solana using blockrun/auto

Notes

Routing is local and completes before payment. Explicit model ids remain unchanged; settled payment errors never advance to a fallback.