feat(09-03): create database seeding fixture for E2E tests

- Add test fixture with seededDb for predictable test data
- Include 5 entries: tasks and thoughts with various states
- Include 3 tags with entry-tag relationships
- Export extended test with fixtures from tests/e2e/index.ts
- Install drizzle-seed dependency

tests/e2e/index.ts

@@ -0,0 +1,7 @@
+/**
+ * E2E test exports with database fixtures
+ *
+ * Import { test, expect } from this file to get tests with seeded database.
+ */
+export { test, testData } from './fixtures/db';
+export { expect } from '@playwright/test';