chore(copilot): update instruction files for copilot

[nineteen88]

Proposed behaviour

Split out the copilot files so that we have instructions for vscode and separate instructions for github copilot

Current behaviour

Currently the instructions are being loaded into context for copilot in vscode and this means there's a lot of information in there that isn't required for it as much of it was for github copilot only. We can separate out the concerns to reduce the context payload and therefore reduce the amount of tokens we use

Checklist

• Commits follow our style guide
• Related issues linked in commit messages if required
• Screenshots are included in the PR if useful
• All themes are supported if required
• Unit tests added or updated if required
• Playwright automation tests added or updated if required
• Storybook added or updated if required
• Translations added or updated (including creating or amending translation keys table in storybook) if required
• Typescript d.ts file added or updated if required
• Related docs have been updated if required

QA

• Tested in provided StackBlitz sandbox/Storybook
• Add new Playwright test coverage if required
• Carbon implementation matches Design System/designs
• UI Tests GitHub check reviewed if required

Additional context

Testing instructions

[Copilot]

Pull request overview

This PR splits Copilot guidance into separate instruction files for VS Code coding assistance vs. GitHub Copilot review, while keeping a smaller shared set of repo conventions.

Changes:

• Adds a VS Code-specific Copilot instruction file and wires it up via workspace settings.
• Introduces a dedicated GitHub Copilot code review instruction file.
• Refactors the existing shared Copilot instructions into a shorter, surface-agnostic document.

Reviewed changes

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

File	Description
.vscode/settings.json	Configures VS Code Copilot Chat code generation to load instructions from .vscode/copilot.md.
.vscode/copilot.md	Adds VS Code-focused coding workflow/testing/preferences guidance (intended to be lighter-weight).
.github/copilot-review-instructions.md	Adds GitHub Copilot review-only checks (breaking changes, skills sync, commit type mismatch, etc.).
.github/copilot-instructions.md	Replaces the prior long-form agent instructions with a condensed shared set of repo/environment/convention notes and references.

Comments suppressed due to low confidence (4)

.vscode/copilot.md:8

• suggestion: align the setup command here with the repo’s stated required environment (shared instructions recommend updating npm to 11.11.1 before running npm run setup) to avoid toolchain mismatches.

1. Setup: `nvm use && npm run setup`
2. Edit `src/`. API/props/behaviour/docs change → `npm run build:skills` + commit result

.github/copilot-instructions.md:40

• issue: the documented npm run build pipeline order is inaccurate (per package.json, the sequence is clean-lib → generate-tokens → type-check → rollup → build:generate-package-json-files → build:move-svg → build:types). Please correct this so contributors follow the real build chain.

| PW CT | `npm run test:ct` (`*.pw.tsx`) |
| Build | `npm run build` (clean→tokens→types→rollup→pkg-jsons→svg→d.ts) |
| Skills | `npm run build:skills -- --check` |

.vscode/copilot.md:10

• issue: this suggests tests live in <name>.test.tsx, but Jest matches both *.spec.* and *.test.* (see jest.config.ts). Document both patterns to avoid contributors creating tests that don’t run.

3. Tests: `<name>.test.tsx` (jsdom, 100% coverage new code). Browser behaviour → `<name>.pw.tsx`
4. Validate (in order): `npm run format` → `npm run lint` → `npm run type-check` → `npm test -- <spec>` → `npm test` → `npm run build:skills -- --check` → `npm run build` (if needed) → `npm run test:ct -- <pw>` (if needed)

.vscode/copilot.md:16

• issue: the example command npm test -- path/to/file.test.tsx is too specific; the repo also uses *.spec.* tests. Consider using a neutral placeholder (e.g. path/to/file.(spec|test).tsx) so the guidance matches the configured testMatch.

- Fast loop: `npm test -- path/to/file.test.tsx`
- Full: `npm test`

[tomdavies73]

suggestion: I think we should tweak this a little bit, the removal of a storybook story shouldn't be considered a breaking change, also removing data- tags or class names is not breaking if they're not exported to consumers.

It may also be worth clarifying that changes to an index.ts is only breaking when it does not sit within an /__internal__/ file path

[nineteen88]

Made changes as requested

[edleeks87]

comment: support for :has() was added in nwsapi 2.3.0 and it looks liek we use 2.3.9

[edleeks87]

question: will this flag the ones we've used in the tokens (old and new) tests? I agree with this beyond them just not sure if they'll be flagged etc

[edleeks87]

comment: we don't support using ! as a breaking change marker

[edleeks87]

question: will this flag findByTestId as well or do we need to explicitly define that?