ci: cache node_modules and Playwright browser binary

node_modules and the Playwright Chromium binary were downloaded fresh
on every run, making setup account for ~99% of pipeline runtime.

- Cache frontend/node_modules keyed on package-lock.json hash
- Cache ~/.cache/ms-playwright keyed on package-lock.json hash
- On cache hit: skip npm ci and browser download, only reinstall
  system deps (install-deps) which is much faster than a full install

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -16,17 +16,36 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: 20
-          cache: npm
-          cache-dependency-path: frontend/package-lock.json
+
+      - name: Cache node_modules
+        id: node-modules-cache
+        uses: actions/cache@v4
+        with:
+          path: frontend/node_modules
+          key: node-modules-${{ hashFiles('frontend/package-lock.json') }}
 
       - name: Install dependencies
+        if: steps.node-modules-cache.outputs.cache-hit != 'true'
         run: npm ci
         working-directory: frontend
 
-      - name: Install Playwright Chromium (used by vitest browser mode)
+      - name: Cache Playwright browsers
+        id: playwright-cache
+        uses: actions/cache@v4
+        with:
+          path: ~/.cache/ms-playwright
+          key: playwright-chromium-${{ hashFiles('frontend/package-lock.json') }}
+
+      - name: Install Playwright Chromium + system deps
+        if: steps.playwright-cache.outputs.cache-hit != 'true'
         run: npx playwright install chromium --with-deps
         working-directory: frontend
 
+      - name: Install Playwright system deps (browser binary already cached)
+        if: steps.playwright-cache.outputs.cache-hit == 'true'
+        run: npx playwright install-deps chromium
+        working-directory: frontend
+
       - name: Run unit and component tests
         run: npm test
         working-directory: frontend
@@ -131,17 +150,36 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: 20
-          cache: npm
-          cache-dependency-path: frontend/package-lock.json
+
+      - name: Cache node_modules
+        id: node-modules-cache
+        uses: actions/cache@v4
+        with:
+          path: frontend/node_modules
+          key: node-modules-${{ hashFiles('frontend/package-lock.json') }}
 
       - name: Install frontend dependencies
+        if: steps.node-modules-cache.outputs.cache-hit != 'true'
         run: npm ci
         working-directory: frontend
 
-      - name: Install Playwright Chromium
+      - name: Cache Playwright browsers
+        id: playwright-cache
+        uses: actions/cache@v4
+        with:
+          path: ~/.cache/ms-playwright
+          key: playwright-chromium-${{ hashFiles('frontend/package-lock.json') }}
+
+      - name: Install Playwright Chromium + system deps
+        if: steps.playwright-cache.outputs.cache-hit != 'true'
         run: npx playwright install chromium --with-deps
         working-directory: frontend
 
+      - name: Install Playwright system deps (browser binary already cached)
+        if: steps.playwright-cache.outputs.cache-hit == 'true'
+        run: npx playwright install-deps chromium
+        working-directory: frontend
+
       # ── Tests ────────────────────────────────────────────────────────────────
       - name: Run E2E tests
         run: npm run test:e2e