feat: add Playwright e2e smoke test covering signup → household → chore flow

- Added smoke.spec.js with Playwright test for full user flow:
  1. Sign up (fill form, submit, click 'Go to Dashboard')
  2. Create household (fill name, submit)
  3. Create chore (fill name + date, submit)
  4. Verify session persistence (revisit dashboard)
- Server now supports --db flag for temp databases and SIS_FRESH_DB env
  to delete the db file on startup (for clean test runs)
- Server reads SIS_PORT env var for port configuration
- scripts/test-e2e: starts server with fresh db, runs tests, cleans up
- playwright.config.js: minimal config pointing at test/e2e/

scripts/test-e2e

@@ -0,0 +1,65 @@
+#!/usr/bin/env bash
+# Run Playwright end-to-end tests.
+#
+# Usage: ./scripts/test-e2e
+#
+# Starts the sis-server with a fresh database, runs the smoke test,
+# then shuts down. Set SIS_URL to test against a running instance:
+#   SIS_URL=http://localhost:8080 ./scripts/test-e2e
+set -euo pipefail
+
+PROJECT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+cd "$PROJECT_DIR"
+
+# Build the server if needed
+BIN="./.stack-work/dist/x86_64-linux/ghc-9.10.3/build/sis-server/sis-server"
+if [ ! -f "$BIN" ]; then
+    echo "[test-e2e] building server..."
+    ./hs stack build --fast
+fi
+
+echo "[test-e2e] running Playwright tests..."
+
+if [ -n "${SIS_URL:-}" ]; then
+    npx playwright test --config=playwright.config.js "$@"
+else
+    DB_PATH="/tmp/sis-test-$$.db"
+    PORT=8081
+
+    # Kill anything already on our test port
+    if lsof -ti:"$PORT" > /dev/null 2>&1; then
+        echo "[test-e2e] killing existing process on port $PORT..."
+        kill "$(lsof -ti:"$PORT")" 2>/dev/null || true
+        sleep 1
+    fi
+
+    # Remove stale db
+    rm -f "$DB_PATH"
+
+    # Clean up on exit
+    cleanup() {
+        rm -f "$DB_PATH"
+        if [ -n "${SERVER_PID:-}" ]; then
+            kill "$SERVER_PID" 2>/dev/null
+            wait "$SERVER_PID" 2>/dev/null || true
+        fi
+    }
+    trap cleanup EXIT
+
+    echo "[test-e2e] starting server on port $PORT with fresh db..."
+    SIS_FRESH_DB=1 SIS_PORT="$PORT" "$BIN" --db "$DB_PATH" &
+    SERVER_PID=$!
+
+    # Wait for server to be ready
+    echo "[test-e2e] waiting for server..."
+    for i in $(seq 1 30); do
+        if curl -sf http://localhost:$PORT/signup > /dev/null 2>&1; then
+            echo "[test-e2e] server ready"
+            break
+        fi
+        sleep 0.5
+    done
+
+    # Run tests
+    SIS_URL="http://localhost:$PORT" npx playwright test --config=playwright.config.js "$@"
+fi