Add custom review instructions to make copilot reviews better

[johnml1135]

Add custom review instructions to make copilot reviews better

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This change is 

[Copilot]

Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.

[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

[jasonleenaylor]

@jasonleenaylor reviewed 7 files and all commit messages, and made 3 comments.
Reviewable status: 7 of 9 files reviewed, all discussions resolved.

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.github/copilot-instructions.md line 22 at r2 (raw file):

  Framework 4.8 / C# 7.3.
- For legacy `.csproj` changes, verify new source files are explicitly included
  and test sources are explicitly excluded where production and test trees mix.

We souldn't have any legacy .csproj files left, do we?

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.github/copilot-instructions.md line 36 at r2 (raw file):

- When those areas change, review null checks, collection bounds, selection
  state, refresh/invalidation behavior, layout anchoring, localization, and
  regression-test coverage before style-only concerns.

I'm not sure of the value of this, this will change from week to week.

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.github/instructions/fieldworks-interop-review.instructions.md line 25 at r2 (raw file):

  where applicable.

## COM and ABI stability

ABI?

[jasonleenaylor]

.github/instructions/fieldworks-parser-utilities-review.instructions.md line 6 at r2 (raw file):

  - "Src/Utilities/AlloVarGen/**"
  - "Src/LexText/ParserCore/**"
  - "Src/LexText/Morphology/**"

Devin flaged this saying the yaml list may not get processed, all other places in the file had ',' separated lists.

[johnml1135]

@jasonleenaylor Follow-up is pushed for the review items.

• .github/copilot-instructions.md: changed the .csproj guidance to call out native/non-SDK projects specifically.
• .github/copilot-instructions.md: removed the entire Review focus from recent history section.
• .github/instructions/fieldworks-interop-review.instructions.md: expanded ABI to binary interface (ABI).

On the applyTo question, I left the YAML list form in place. The VS Code Copilot custom instructions documentation shows both forms as supported:

• array/list syntax: applyTo: ["src/**", "lib/**"]
• comma-separated syntax: applyTo: src/**, lib/**

Docs: https://code.visualstudio.com/docs/copilot/customization/custom-instructions

[jasonleenaylor]

@jasonleenaylor made 1 comment.
Reviewable status: 7 of 9 files reviewed, all discussions resolved.