feat(books): add read-aloud generation

Generate a synced read-aloud EPUB from a book's EPUB and audiobook through an
optional STAlign worker (Docker on CPU, or native with MLX on Apple Silicon),
with review, re-sync, replace in place, restart recovery and live progress on
the Files tab. Book details also stack the ebook and audiobook covers when
both exist. See docs/READ_ALOUD.md.

.github/actions/setup-node-pnpm/action.yml

@@ -63,7 +63,11 @@ runs:
       shell: bash
       run: pnpm fetch --frozen-lockfile
 
+    # onnxruntime-node's postinstall otherwise downloads its CUDA provider on Linux x64. Nothing in CI
+    # uses it, and the CPU binding the read-aloud worker tests load ships in the npm package itself.
     - name: Install dependencies
       if: ${{ inputs.install == 'true' }}
       shell: bash
+      env:
+        ONNXRUNTIME_NODE_INSTALL: skip
       run: pnpm install --frozen-lockfile