ci: remove cross-platform matrix (blocked on GitHub billing)

GitHub-hosted runners fail for this private repo with 'recent account
payments have failed or your spending limit needs to be increased.'
Reverting the ubuntu-latest and windows-latest unit test matrix until
billing is resolved or the repo goes public.

Trivy and Gitleaks on self-hosted confirmed working.

Signed-off-by: Sebastien Tardif <sebtardif@ncf.ca>

Author: SebTardif

.github/workflows/ci.yml

@@ -36,29 +36,6 @@ jobs:
       - name: Run tests
         run: npm test
 
-  unit-test-cross-platform:
-    strategy:
-      fail-fast: false
-      matrix:
-        os: [ubuntu-latest, windows-latest]
-    runs-on: ${{ matrix.os }}
-    timeout-minutes: 10
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v6
-
-      - name: Setup Node.js
-        uses: actions/setup-node@v6
-        with:
-          node-version-file: .nvmrc
-          cache: npm
-
-      - name: Install dependencies
-        run: npm ci
-
-      - name: Run tests
-        run: npm test
-
   build:
     runs-on:
       - self-hosted

AGENTS.md

@@ -69,7 +69,7 @@ scripts/
     feature-request.yml    Feature request form
   PULL_REQUEST_TEMPLATE.md PR template
   workflows/
-    ci.yml                 CI: unit tests (self-hosted + cross-platform matrix), build, integration tests
+    ci.yml                 CI: unit tests, build, integration tests (self-hosted)
     dependabot-auto-merge.yml  Auto-merge minor/patch Dependabot PRs
     security.yml           Security: npm audit, Trivy fs scan, Gitleaks (weekly + on push/PR)
 ```

CHANGELOG.md

@@ -34,6 +34,5 @@
 - CI on self-hosted runner with npm audit security scanning (weekly schedule)
 - Trivy filesystem vulnerability and misconfiguration scanning
 - Gitleaks secret detection across full commit history
-- Cross-platform unit test matrix (Ubuntu, Windows, macOS)
 - Dependabot auto-merge for minor and patch dependency updates
 - Extension packaging with `@vscode/vsce`