fix(ci): use pnpm ... filter to build all workspace deps (AUD-239)

Replace three manual build steps with a single
`pnpm --filter @imtbl/audience... build` which automatically builds all
transitive workspace dependencies in the correct order, matching the
pattern already used in audience-bundle-size.yaml.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: nattb8

.github/workflows/deploy-audience-cdn.yaml

@@ -32,14 +32,8 @@ jobs:
       - name: setup
         uses: ./.github/actions/setup
 
-      - name: Build metrics
-        run: pnpm --filter @imtbl/metrics build
-
-      - name: Build audience-core
-        run: pnpm --filter @imtbl/audience-core build
-
       - name: Build audience SDK bundle
-        run: pnpm --filter @imtbl/audience build
+        run: pnpm --filter @imtbl/audience... build
 
       - name: Verify bundle exists
         run: |