Update LICENSE copyright and add AI attribution instructions

[jerrysxie]

This PR applies two org-wide standardisation changes
(ref: OpenDevicePartnership/embedded-rust-template#20):

1. LICENSE – normalise the copyright line to:
   Copyright (c) Open Device Partnership and Contributors

2. .github/copilot-instructions.md – add the Commit Messages and
   AI Attribution sections so every repo carries consistent guidance
   for contributors and AI agents.

[Copilot]

Pull request overview

Applies org-wide standardization updates by normalizing the MIT LICENSE copyright holder line and adding repository-level guidance for commit message formatting and AI attribution via Copilot instructions.

Changes:

• Update the LICENSE copyright line to “Open Device Partnership and Contributors”.
• Add .github/copilot-instructions.md with commit message conventions and an Assisted-by trailer format for AI-assisted work.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
LICENSE	Normalizes the MIT license copyright holder line to the org standard.
.github/copilot-instructions.md	Adds standardized contributor/agent guidance for commit messages and AI attribution trailers.

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