Add self-contained e2e test harness with ephemeral PocketBase

Previously, 15 e2e tests were skipped because TEST_USER_EMAIL and
TEST_USER_PASSWORD env vars weren't set. Now the test harness:

- Starts a fresh PocketBase instance in /tmp on port 8091
- Creates admin user, collections, and API rules automatically
- Seeds test user with period data for authenticated tests
- Cleans up temp directory after tests complete

Also fixes:
- Override toggle tests now use checkbox role (not button)
- Adds proper wait for OVERRIDES section before testing toggles
- Suppresses document.cookie lint warning with explanation

Test results: 64 e2e tests pass, 1014 unit tests pass

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

vitest.config.ts

@@ -13,7 +13,11 @@ export default defineConfig({
   },
   test: {
     environment: "jsdom",
-    include: ["src/**/*.test.{ts,tsx}", "scripts/**/*.test.ts"],
+    include: [
+      "src/**/*.test.{ts,tsx}",
+      "scripts/**/*.test.ts",
+      "e2e/**/*.test.ts",
+    ],
     setupFiles: ["./src/test-setup.ts"],
   },
 });