fix(ci): add bun setup to build and nightly workflows

go:generate in pkg/miniapp/miniapp.go requires bun to build the
Mini App frontend. The PR workflow had it, but build and nightly
were missing it.

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

.github/workflows/build.yml

@@ -16,5 +16,11 @@ jobs:
         with:
           go-version-file: go.mod
 
+      - name: Setup Bun
+        uses: oven-sh/setup-bun@v2
+
+      - name: Install frontend dependencies
+        run: cd pkg/miniapp/frontend && bun install --frozen-lockfile
+
       - name: Build
         run: make build-all

.github/workflows/nightly.yml

@@ -55,6 +55,12 @@ jobs:
       - name: Setup pnpm
         run: corepack enable && corepack prepare pnpm@latest --activate
 
+      - name: Setup Bun
+        uses: oven-sh/setup-bun@v2
+
+      - name: Install miniapp frontend deps
+        run: cd pkg/miniapp/frontend && bun install
+
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v3