CI: Build, test, and package both plugins on every PR #54

Goal

Build, test, and package both plugins automatically on every pull request.

Acceptance criteria

• VS Code CI runs npm ci, type checking, automated tests, and VSIX packaging.
• Eclipse has a reproducible build/test workflow.
• CI publishes or retains the package/build artifact for review when practical.
• CI uses the shared regression corpus as a required quality gate.

Evidence

Link successful workflow runs for one VS Code pull request and one Eclipse change.