chore(harness): run changed suites in CI

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

.github/workflows/harness-validate.yml

@@ -52,13 +52,17 @@ jobs:
 
           echo "to=${GITHUB_SHA}" >> "$GITHUB_OUTPUT"
 
-      - name: Show selected harness suites
-        run: pnpm harness:select -- --from "${{ steps.range.outputs.from }}" --to "${{ steps.range.outputs.to }}"
+      - name: Run selected harness suites
+        run: pnpm harness:validate:changed -- --from "${{ steps.range.outputs.from }}" --to "${{ steps.range.outputs.to }}"
 
-      - name: Run PR harness suite on pull requests
-        if: github.event_name == 'pull_request'
-        run: pnpm harness:validate:pr
-
-      - name: Run PR harness suite on main
-        if: github.event_name == 'push'
-        run: pnpm harness:validate:pr
+      - name: Upload harness artifacts
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: harness-artifacts-${{ github.run_id }}-${{ github.run_attempt }}
+          if-no-files-found: ignore
+          path: |
+            .artifacts/harness
+            .artifacts/a11y
+            .artifacts/test-results
+          retention-days: 7