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/

package-lock.json

@@ -5,9 +5,25 @@
   "packages": {
     "": {
       "dependencies": {
+        "@playwright/test": "^1.61.1",
         "playwright": "^1.61.1"
       }
     },
+    "node_modules/@playwright/test": {
+      "version": "1.61.1",
+      "resolved": "https://registry.npmjs.org/@playwright/test/-/test-1.61.1.tgz",
+      "integrity": "sha512-8nKv6+0RJSL9FE4jYOEGXnPeM/Hg12qZpmqzZjRh3qM0Y7c3z1mrOTfFLids72RDQYVh9WpLEfR5WdpNX4fkig==",
+      "license": "Apache-2.0",
+      "dependencies": {
+        "playwright": "1.61.1"
+      },
+      "bin": {
+        "playwright": "cli.js"
+      },
+      "engines": {
+        "node": ">=18"
+      }
+    },
     "node_modules/fsevents": {
       "version": "2.3.2",
       "resolved": "https://registry.npmjs.org/fsevents/-/fsevents-2.3.2.tgz",