v0.1.0 of aimarket_agent

AI Market Protocol v2 consumer SDK for Dart/Flutter. Discover, purchase, and invoke AI capabilities from the decentralized marketplace. Changelog excerpt: Initial release of the Dart consumer SDK for AI Market Protocol v2. - AimarketAgent— discover → open channel → invoke → settle lifecycle. - MarketSigner— Ed25519 canonical signatures and EIP-712 channel-debit signatures. - TEE attestation verification (TeeVerifier). - Data models with JSON round-trip: Capability, Channel, InvokeResult, TeeAttestation, TeeReceipt, PlanStep, Settlement, BillOfMaterials, SearchResponse.