chore: remove duplicate build step from release workflow

The release job was building twice: once explicitly via `pnpm build`,
then again inside `pnpm release` which runs `pnpm build && changeset publish`.
Remove the standalone build step since the changesets publish command
already handles it.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ryanbas21

.github/workflows/release.yml

@@ -61,11 +61,6 @@ jobs:
 
       - run: pnpm install --frozen-lockfile
 
-      - name: Build
-        run: pnpm build
-        env:
-          BUILD_NUMBER: ${{ github.run_number }}
-
       - name: Create release PR or publish
         id: changesets
         uses: changesets/action@63a615b9cd06ba9a3e6d13796c7fbcb080a60a0b # v1.8.0