docs: update contribute and ai instructions

[rsdmike]

PR Checklist

• Unit Tests have been added for new changes
• API tests have been updated if applicable
• All commented code has been removed
• If you've added a dependency, you've ensured license is compatible with Apache 2.0 and clearly outlined the added dependency.

What are you changing?

Anything the reviewer should know when reviewing this PR?

If the there are associated PRs in other repositories, please link them here (i.e. device-management-toolkit/repo#365 )

[Copilot]

Pull request overview

This PR updates contributor guidance and adds a canonical, tool-neutral set of AI assistant instructions for working in the MPS repository, with pointers from common instruction entrypoints.

Changes:

• Update commit footer guidance in CONTRIBUTING.md to reference GitHub issues instead of Azure Boards/JIRA.
• Add CLAUDE.md as the canonical AI assistant guide (architecture, commands, and non-negotiable implementation guidelines).
• Add pointer files (AGENTS.md, .github/copilot-instructions.md) that redirect agents to CLAUDE.md.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
CONTRIBUTING.md	Switches commit footer references to GitHub issues and updates examples accordingly.
CLAUDE.md	Introduces a centralized AI assistant guide describing repo architecture, workflows, and rules of engagement.
AGENTS.md	Adds a minimal pointer directing agents to CLAUDE.md.
.github/copilot-instructions.md	Adds Copilot-specific pointer + concise “non-negotiables” summary linking back to CLAUDE.md.

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[rsdmike]

Tracking issue: device-management-toolkit/deployment#568 — device-management-toolkit/deployment#568