sessions - clarify instructions around compiling and testing

[bpasero]

No description provided.

[Copilot]

Pull request overview

This PR updates contributor-facing documentation to make TypeScript compilation and test-running guidance clearer for the agent sessions area and for Copilot instruction users.

Changes:

• Updates the sessions skill doc to point to scripts/test.sh / scripts\test.bat for running unit tests (with --grep filtering).
• Adds an explicit warning in the sessions skill doc to avoid running tsc directly for validation.
• Updates Copilot instructions to use npm run gulp compile-extensions (instead of gulp compile-extensions) when validating built-in extension changes without the build task.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
.github/skills/sessions/SKILL.md	Clarifies how to run unit tests and adds guidance about TypeScript validation workflow.
.github/copilot-instructions.md	Adjusts extension compilation guidance to use the repo’s npm run gulp script wrapper.

Comments suppressed due to low confidence (2)

.github/skills/sessions/SKILL.md:275

• List item 3 is the only one in this section without ending punctuation, which makes the list inconsistent with items 1–2. Consider adding a trailing period (and optionally a semicolon-free parenthetical) to match the surrounding style.

3. Use `scripts/test.sh` (or `scripts\test.bat` on Windows) for unit tests (add `--grep <pattern>` to filter tests)

.github/skills/sessions/SKILL.md:277

• This reads as a run-on sentence and is missing punctuation/capitalization. Consider rewriting as "Important: Do not run tsc to check for TypeScript errors; always use the methods above to validate TypeScript changes in src/vs/**."

**Important** do not run `tsc` to check for TypeScript errors always use above methods to validate TypeScript changes in `src/vs/**`.