ci(traceability): enable corepack so the SDK build can use pnpm (#289)

The refresh run failed with 'pnpm: not found' — the reference SDK's
build command (typescript-sdk: pnpm install && pnpm run build:all) needs
pnpm on PATH. Add 'corepack enable' to the run job.

Author: pcarleton

.github/workflows/traceability.yml

@@ -42,6 +42,10 @@ jobs:
           node-version: 24
           cache: npm
 
+      # The SDK's own build (e.g. typescript-sdk uses `pnpm install && pnpm run
+      # build:all`) needs pnpm on PATH; corepack provides it.
+      - run: corepack enable
+
       - run: npm ci
       - run: npm run build