Feature — Contribution Guide & Adapter SDK

[coderkrp]

As a contributor,
I want clear docs and SDK examples,
So that I can add new brokers easily.

Acceptance criteria

• AC1: A CONTRIBUTING.md file is created at the root of the project.
• AC2: The guide explains the adapter architecture and the process for adding a new broker.
• AC3: It includes a small "Adapter SDK" section with code snippets for the IBrokerAdapter interface.
• AC4: It outlines the requirements for unit tests and documentation for new adapters.

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)