ci: bump checkout/setup-node to v5 (Node 24 runtime), build with Node 22

GitHub forces actions onto the Node 24 runtime on 2026-06-16; checkout@v4
and setup-node@v4 are Node 20 actions and were flagged on both the Windows
and macOS build jobs. Node 20 itself is EOL (April 2026), so the app build
moves to Node 22 LTS.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: davidtorcivia

.github/workflows/build.yml

@@ -23,7 +23,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: Install Rust stable
         uses: dtolnay/rust-toolchain@stable
@@ -38,9 +38,9 @@ jobs:
           workspaces: src-tauri -> target
 
       - name: Install Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v5
         with:
-          node-version: 20
+          node-version: 22
 
       - name: Install npm dependencies
         run: npm ci