Install Playwright browsers in CI test jobs

The e2e tests launch chromium, but uv sync only installs the playwright
package, not the browser binaries, so CI failed with "Executable
doesn't exist" for the headless shell.

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

.gitea/workflows/build.yml

@@ -19,6 +19,9 @@ jobs:
       - name: Install dependencies
         run: uv sync --frozen
 
+      - name: Install Playwright browsers
+        run: uv run playwright install --with-deps chromium
+
       - name: Run Migrations
         run: uv run python manage.py migrate
 

.github/workflows/build-docker.yml

@@ -19,6 +19,9 @@ jobs:
       - name: Install dependencies
         run: uv sync --frozen
 
+      - name: Install Playwright browsers
+        run: uv run playwright install --with-deps chromium
+
       - name: Run Migrations
         run: uv run python manage.py migrate