Feature — Pre-Trade Validation & Retries

[coderkrp]

As a trader,
I want Ordo to validate trades and retry failures,
So that my orders have the best chance of success.

Acceptance criteria

• AC1: The orchestrator performs pre-trade validation checks (instrument tradability, funds) before placing an order (FR13, FR14).
• AC2: If validation fails, the request is rejected immediately with a clear error (FR15).
• AC3: The orchestrator automatically retries failed broker calls for transient errors (e.g., network issues, 5xx errors) using an exponential backoff strategy (FR10).
• AC4: The number of retries and backoff factor are configurable.

Definition of Done

• Code implemented in a feature/fix branch
• Unit / integration tests added or existing tests updated
• Linting passed and code builds locally
• Docs / README updated if behavior changed
• PR opened and linked (Closes #<issue-number>)
• Manual QA steps verified (if applicable)