[Breaking] Add TradeId and remove raw Uuid from execution API

[j-b-layerv]

Description

Introduce a dedicated TradeId newtype and replace raw Uuid usage in execution models with domain-safe identifiers.

Depends on

• [Breaking] Rename execution domain: Transaction -> Trade #8

Problem

The execution domain currently exposes raw Uuid in public APIs, which weakens type safety and allows accidental mixups with other IDs.

Scope

• Add TradeId as first-class identifier type.
• Replace transaction_id: Uuid with trade_id: TradeId in Trade.
• Update parser/formatter/serde behavior.
• Update matching flow to generate/propagate TradeId.

Tasks

• Add TradeId type (constructor(s), parse, display, serde).
• Replace ID field in Trade model and constructor signature.
• Update ID generation usage in src/price_level/level.rs.
• Update all tests touching execution IDs.
• Update docs/examples using raw UUID for trades.

Technical Details

Candidate files:

• src/execution/transaction.rs (after [Breaking] Rename execution domain: Transaction -> Trade #8: trade.rs if renamed)
• src/utils/uuid.rs (if adaptation needed)
• src/price_level/level.rs
• src/execution/tests/*

Breaking Changes

• Execution model ID field/type changes to TradeId.
• Constructor and serialization contract changes accordingly.

Acceptance Criteria

• No raw Uuid appears in public execution model API.
• TradeId supports roundtrip parse/display/serde.
• Full suite passes (fmt, clippy -D warnings, test, release build).

Out of Scope

• Introducing Price/Quantity/TimestampMs wrappers for all APIs.

[joaquinbejar]

Recreated as #18 (#18) using the correct author account (joaquinbejar). Closing this issue to avoid duplicate tracking.