fix(front-end): button calculator

.gitea/workflows/pr-checks.yaml

@@ -150,23 +150,36 @@ jobs:
           cache: "npm"
           cache-dependency-path: "frontend/package-lock.json"
 
-      - name: Install Chromium
+      - name: Resolve Chrome binary
         shell: bash
         run: |
-          apt-get update
-          apt-get install -y --no-install-recommends chromium
+          set -euo pipefail
+          if command -v chromium >/dev/null 2>&1; then
+            CHROME_PATH="$(command -v chromium)"
+          elif command -v chromium-browser >/dev/null 2>&1; then
+            CHROME_PATH="$(command -v chromium-browser)"
+          elif command -v google-chrome >/dev/null 2>&1; then
+            CHROME_PATH="$(command -v google-chrome)"
+          else
+            apt-get update
+            apt-get install -y --no-install-recommends chromium
+            CHROME_PATH="$(command -v chromium)"
+          fi
+
+          echo "CHROME_BIN=$CHROME_PATH" >> "$GITHUB_ENV"
+          echo "Using CHROME_BIN=$CHROME_PATH"
 
       - name: Install frontend dependencies
         shell: bash
         run: |
           cd frontend
-          npm ci --no-audit --no-fund
+          npm ci --no-audit --no-fund --prefer-offline
 
       - name: Run frontend tests (headless)
         shell: bash
         env:
-          CHROME_BIN: /usr/bin/chromium
           CI: "true"
         run: |
           cd frontend
+          echo "Karma CHROME_BIN=$CHROME_BIN"
           npm run test -- --watch=false --browsers=ChromeHeadlessNoSandbox