fix(ci): setup MSVC for x86 to fix dependency builds

The x86 (32-bit) build job was failing at 'Install dependencies'
(uv sync) because packages like pyyaml and greenlet lack cp314-win32
wheels for Python 3.14 and must be built from sdist. Building on
Windows requires the 32-bit MSVC toolchain, which was not activated.

Added:
- name: Setup MSVC for x86
  if: matrix.arch == 'x86'
  uses: ilammy/msvc-dev-cmd@v1
  with:
    arch: x86

This complements the cryptography>=46,<49 pin (to avoid builds
where possible) and allows the x86 matrix entry to succeed for
dependabot PRs like #1260 (google-genai) and similar.

Author: AAClause

.github/workflows/build_app.yml

@@ -44,6 +44,11 @@ jobs:
         with:
           python-version: 'cpython-3.14-windows-${{ matrix.arch }}-none'
           working-directory: ${{ github.workspace }}/repo
+      - name: Setup MSVC for x86
+        if: matrix.arch == 'x86'
+        uses: ilammy/msvc-dev-cmd@v1
+        with:
+          arch: x86
       - name: Install dependencies
         working-directory: ${{ github.workspace }}/repo
         run: uv sync --frozen --compile --group build --group test