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>

src/lib/pocketbase.ts

@@ -24,8 +24,11 @@ pb.autoCancellation(false);
 // Sync auth state to cookie on any change (login, logout, token refresh)
 // This allows Next.js middleware to read auth state for route protection
 // Cookie is non-HttpOnly because the client-side SDK needs read/write access
+// Using document.cookie is intentional here - Cookie Store API has limited browser
+// support and PocketBase SDK's exportToCookie() returns a cookie string format
 if (typeof window !== "undefined") {
   pb.authStore.onChange(() => {
+    // biome-ignore lint/suspicious/noDocumentCookie: PocketBase SDK requires document.cookie for auth sync
     document.cookie = pb.authStore.exportToCookie({ httpOnly: false });
   });
 }