M3 #27: Rust SDK: Instruction builders for transaction construction

[joaquinbejar]

Summary

Implements instruction builders that construct Solana transactions for all Matchbook operations. These builders handle account resolution, PDA derivation, and instruction serialization.

Changes

New Module: sdk/src/instructions/

File	Description
mod.rs	Module exports
pda.rs	PDA derivation utilities
create_market.rs	CreateMarketBuilder
create_open_orders.rs	CreateOpenOrdersBuilder
deposit.rs	DepositBuilder
withdraw.rs	WithdrawBuilder
place_order.rs	PlaceOrderBuilder
cancel_order.rs	CancelOrderBuilder
cancel_all_orders.rs	CancelAllOrdersBuilder
match_orders.rs	MatchOrdersBuilder
consume_events.rs	ConsumeEventsBuilder

Instruction Builders

• CreateMarketBuilder: Create new market with all associated PDAs
• CreateOpenOrdersBuilder: Create user's open orders account
• DepositBuilder: Deposit base/quote tokens
• WithdrawBuilder: Withdraw base/quote tokens
• PlaceOrderBuilder: Place order with side, price, quantity, order type
• CancelOrderBuilder: Cancel specific order by ID
• CancelAllOrdersBuilder: Cancel all orders with optional side filter
• MatchOrdersBuilder: Trigger order matching with maker accounts
• ConsumeEventsBuilder: Process events with user accounts

PDA Derivation Utilities

• derive_market_address: Seeds [b"market", base_mint, quote_mint]
• derive_bids_address: Seeds [market, b"bids"]
• derive_asks_address: Seeds [market, b"asks"]
• derive_event_queue_address: Seeds [market, b"event_queue"]
• derive_base_vault_address: Seeds [market, b"base_vault"]
• derive_quote_vault_address: Seeds [market, b"quote_vault"]
• derive_open_orders_address: Seeds [b"open_orders", market, owner]
• MarketPdas: Derive all market PDAs at once

Builder Pattern Features

• Fluent API with method chaining
• Automatic PDA derivation
• Borsh serialization for instruction data
• Error handling for missing required fields
• Optional fields with sensible defaults

Dependencies

• Add solana-sdk v2.2 to workspace
• Add borsh v1.5 to workspace

Technical Decisions

• Builder pattern: Each instruction uses a builder with fluent API for ergonomic construction
• Automatic PDA derivation: Builders derive all required PDAs automatically
• Borsh serialization: Instruction data serialized with borsh matching on-chain format
• Placeholder discriminators: Using placeholder values; actual discriminators will match on-chain program

Testing

• 54 unit tests for instruction builders
• PDA derivation tests
• Builder chain tests
• Missing field error tests
• Account list verification tests

Checklist

• Code follows .internalDoc/09-rust-guidelines.md
• Documentation added for all public items
• No warnings from cargo clippy
• cargo fmt passes
• All tests pass

Closes #27