Remove pr-quality workflow per user request

[Copilot]

Summary

Removed .github/workflows/pr-quality.yml workflow and all documentation references per maintainer request—copilot-instructions alone sufficient for AI-assisted development guidance.

Root Cause (for bug fixes)

N/A - Not a bug fix, configuration removal.

Description of Change

• Deleted .github/workflows/pr-quality.yml (automated PR build/test workflow with Release-Xml configuration)
• Updated .github/instructions/copilot-instructions.md:
  • Section 4 (line 53): Removed pr-quality workflow mention; retained core CI pipeline reference
  • Section 16: Removed "PR Quality Workflow" subsection; kept pipelines/build.yml documentation only

Rationale: Maintainer prefers relying on copilot-instructions for development guidance without automated PR workflow enforcement.

Issues Fixed / Linked

Fixes #292 (comment feedback)

Impact/Risk

Low. Removes automated PR checks—developers must run Release-Xml builds locally before submission. No code or library functionality affected.

Checklist

• Multi-target build succeeds (all TFMs) - N/A documentation only
• Release-Xml build passes with zero warnings - N/A documentation only
• New/updated unit tests added & passing - N/A documentation only
• XML docs updated for changed public APIs - N/A no API changes
• No silent breaking changes (or migration notes included) - N/A
• Platform parity (Android/iOS/MacCatalyst/Windows) maintained or stubbed - N/A
• Performance unaffected / profiled (explain if risk exists) - N/A
• No memory leaks (events/timers disposed) - N/A
• Samples updated if UX/API changed - N/A
• Themes/styles consistent; no orphaned resource keys - N/A
• Accessibility semantics (focus, descriptions) validated - N/A
• PR description explains root cause & fix clearly

Screenshots / Visuals (if UI)

N/A - Documentation and workflow configuration changes only.

Additional Notes

Contributors should continue following copilot-instructions.md for build/test guidance, including local Release-Xml validation before PR submission.

Reviewer Guidance

Verify copilot-instructions.md accurately reflects CI pipeline (pipelines/build.yml) without pr-quality workflow references.

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✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[github-actions]

Thanks for opening this PR! Please ensure the Quality Assurance Checklist in .github/instructions/copilot-instructions.md is fully addressed:

• Multi-target build (Release-Xml) success
• Analyzer warnings resolved
• Tests added/updated and passing
• XML docs for public API changes
• Platform parity & accessibility
• Performance & memory considerations
  If any item is not applicable, clarify reasoning in the PR description.