ci: use reproducible installs

Author: metonym

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ jobs:
           key: ${{ runner.os }}-playwright-${{ hashFiles('**/bun.lock') }}
 
       - name: Install dependencies
-        run: bun install
+        run: bun ci
 
       - name: Install Playwright binaries
         run: bunx playwright install --with-deps