Add copilot-instructions.md

[JamieMagee]

Generated by Claude Sonnet 4.5 using the following prompt

Analyze this codebase to generate or update `.github/copilot-instructions.md` for guiding AI coding agents.

Focus on discovering the essential knowledge that would help an AI agents be immediately productive in this codebase. Consider aspects like:
- The "big picture" architecture that requires reading multiple files to understand - major components, service boundaries, data flows, and the "why" behind structural decisions
- Critical developer workflows (builds, tests, debugging) especially commands that aren't obvious from file inspection alone
- Project-specific conventions and patterns that differ from common practices
- Integration points, external dependencies, and cross-component communication patterns

Source existing AI conventions from `**/{.github/copilot-instructions.md,AGENT.md,AGENTS.md,CLAUDE.md,.cursorrules,.windsurfrules,.clinerules,.cursor/rules/**,.windsurf/rules/**,.clinerules/**,README.md}` (do one glob search).

Guidelines (read more at https://aka.ms/vscode-instructions-docs):
- If `.github/copilot-instructions.md` exists, merge intelligently - preserve valuable content while updating outdated sections
- Write concise, actionable instructions (~20-50 lines) using markdown structure
- Include specific examples from the codebase when describing patterns
- Avoid generic advice ("write tests", "handle errors") - focus on THIS project's specific approaches
- Document only discoverable patterns, not aspirational practices
- Reference key files/directories that exemplify important patterns

Update `.github/copilot-instructions.md` for the user, then ask for feedback on any unclear or incomplete sections to iterate.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.3%. Comparing base (c8d244c) to head (59004d0).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #1524   +/-   ##
=====================================
  Coverage   90.3%   90.3%           
=====================================
  Files        418     418           
  Lines      35275   35275           
  Branches    2188    2188           
=====================================
+ Hits       31881   31882    +1     
  Misses      2951    2951           
+ Partials     443     442    -1     

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