test: add end-to-end browser tests with Playwright

Set up tests/e2e/ with a login page test covering branding, accessibility,
form structure, theme colors, and static asset serving. Includes run.sh
that manages the app lifecycle (start, test, stop) automatically.

tests/e2e/run.sh

@@ -0,0 +1,78 @@
+#!/usr/bin/env bash
+# Run Porchlight end-to-end browser tests.
+#
+# Usage:
+#   ./run.sh              # run all test_*.js files
+#   ./run.sh test_login.js  # run a specific test
+#
+# Prerequisites:
+#   npm install && npm run setup   (once, to install playwright + chromium)
+#
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+
+PORT="${E2E_PORT:-8099}"
+export TARGET_URL="http://127.0.0.1:${PORT}"
+
+# --- Start the app ---
+echo "Starting Porchlight on port ${PORT}..."
+OIDC_OP_ISSUER="${TARGET_URL}" \
+OIDC_OP_DEBUG=true \
+OIDC_OP_SQLITE_PATH=:memory: \
+  uv run --directory "$PROJECT_ROOT" \
+  uvicorn fastapi_oidc_op.app:create_app \
+    --factory --host 127.0.0.1 --port "$PORT" \
+    --log-level warning &
+SERVER_PID=$!
+
+cleanup() {
+  echo "Stopping server (pid ${SERVER_PID})..."
+  kill "$SERVER_PID" 2>/dev/null || true
+  wait "$SERVER_PID" 2>/dev/null || true
+}
+trap cleanup EXIT
+
+# --- Wait for healthy ---
+echo "Waiting for server..."
+for i in $(seq 1 30); do
+  if curl -sf "${TARGET_URL}/health" >/dev/null 2>&1; then
+    echo "Server ready."
+    break
+  fi
+  if [ "$i" -eq 30 ]; then
+    echo "Server failed to start within 30 seconds." >&2
+    exit 1
+  fi
+  sleep 1
+done
+
+# --- Run tests ---
+FAILED=0
+
+if [ $# -gt 0 ]; then
+  TEST_FILES=("$@")
+else
+  TEST_FILES=("$SCRIPT_DIR"/test_*.js)
+fi
+
+for test_file in "${TEST_FILES[@]}"; do
+  echo ""
+  echo "=== Running $(basename "$test_file") ==="
+  if node "$test_file"; then
+    echo "=== $(basename "$test_file"): OK ==="
+  else
+    echo "=== $(basename "$test_file"): FAILED ==="
+    FAILED=1
+  fi
+done
+
+echo ""
+if [ "$FAILED" -eq 0 ]; then
+  echo "All e2e tests passed."
+else
+  echo "Some e2e tests failed." >&2
+fi
+
+exit "$FAILED"