chore(ci): bump actions/checkout@v5 + setup-node@v5 + node 22 (#24)

GH Actions has been emitting deprecation warnings on every CI
run:

  Node.js 20 actions are deprecated. The following actions are
  running on Node.js 20 and may not work as expected: actions/
  checkout@v4, actions/setup-node@v4.

setup-node@v5 (and checkout@v5) run on Node 24 by default; bump
the engines target to node 22 as a stable LTS that's well-tested
with both Vite and Playwright. (Local dev still works on whatever
the dev has — these versions only affect CI runners.)

Author: mastermanas805

.github/workflows/ci.yml

@@ -10,11 +10,11 @@ jobs:
   build-and-test:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
-      - uses: actions/setup-node@v4
+      - uses: actions/setup-node@v5
         with:
-          node-version: '20'
+          node-version: '22'
           cache: 'npm'
 
       - run: npm ci
@@ -24,11 +24,11 @@ jobs:
   playwright:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
-      - uses: actions/setup-node@v4
+      - uses: actions/setup-node@v5
         with:
-          node-version: '20'
+          node-version: '22'
           cache: 'npm'
 
       - run: npm ci