fix(ci): pin ilammy/msvc-dev-cmd to commit hash for supply-chain security

- Pin from @v1 (mutable tag) to full SHA 0b201ec74fa43914dc39ae48a89fd1d8cb592756 (v1.13.0)
- All other actions in the workflow are already pinned to commits
- Addresses supply-chain risk and zizmor blanket pinning policy

Author: AAClause

.github/workflows/build_app.yml

@@ -46,7 +46,7 @@ jobs:
           working-directory: ${{ github.workspace }}/repo
       - name: Setup MSVC for x86
         if: matrix.arch == 'x86'
-        uses: ilammy/msvc-dev-cmd@v1
+        uses: ilammy/msvc-dev-cmd@0b201ec74fa43914dc39ae48a89fd1d8cb592756 # v1.13.0
         with:
           arch: x86
       - name: Install dependencies