Add Playwright e2e tests for all 8 spec acceptance scenarios

Implement browser-based e2e tests covering:
- Tests 1-5: Stats progression (cohort, feed, eggs, moves, backdating)
- Test 6: Event viewing and deletion UI
- Test 7: Harvest outcomes with yield items
- Test 8: Optimistic lock selection validation

Includes page objects for reusable form interactions and fresh_db
fixtures for tests requiring isolated database state.

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

tests/e2e/conftest.py

@@ -120,3 +120,96 @@ def live_server(e2e_db_path):
 def base_url(live_server):
     """Provide the base URL for the live server."""
     return live_server.url
+
+
+# =============================================================================
+# Function-scoped fixtures for tests that need isolated state
+# =============================================================================
+
+
+def _create_fresh_db(tmp_path) -> str:
+    """Create a fresh migrated and seeded database.
+
+    Helper function used by function-scoped fixtures.
+    """
+    db_path = str(tmp_path / f"animaltrack_{random.randint(0, 99999)}.db")
+    run_migrations(db_path, "migrations", verbose=False)
+    db = get_db(db_path)
+    run_seeds(db)
+    return db_path
+
+
+@pytest.fixture
+def fresh_db_path(tmp_path):
+    """Create a fresh database for a single test.
+
+    Function-scoped so each test gets isolated state.
+    Use this for tests that need a clean slate (e.g., deletion, harvest).
+    """
+    return _create_fresh_db(tmp_path)
+
+
+@pytest.fixture
+def fresh_server(fresh_db_path):
+    """Start a fresh server for a single test.
+
+    Function-scoped so each test gets isolated state.
+    This fixture is slower than the session-scoped live_server,
+    so only use it when you need a clean database for each test.
+    """
+    port = 33760 + random.randint(0, 99)
+    harness = ServerHarness(port)
+    harness.start(fresh_db_path)
+    yield harness
+    harness.stop()
+
+
+@pytest.fixture
+def fresh_base_url(fresh_server):
+    """Provide the base URL for a fresh server."""
+    return fresh_server.url
+
+
+# =============================================================================
+# Page object fixtures
+# =============================================================================
+
+
+@pytest.fixture
+def animals_page(page, base_url):
+    """Page object for animal management."""
+    from tests.e2e.pages import AnimalsPage
+
+    return AnimalsPage(page, base_url)
+
+
+@pytest.fixture
+def feed_page(page, base_url):
+    """Page object for feed management."""
+    from tests.e2e.pages import FeedPage
+
+    return FeedPage(page, base_url)
+
+
+@pytest.fixture
+def eggs_page(page, base_url):
+    """Page object for egg collection."""
+    from tests.e2e.pages import EggsPage
+
+    return EggsPage(page, base_url)
+
+
+@pytest.fixture
+def move_page(page, base_url):
+    """Page object for animal moves."""
+    from tests.e2e.pages import MovePage
+
+    return MovePage(page, base_url)
+
+
+@pytest.fixture
+def harvest_page(page, base_url):
+    """Page object for harvest/outcome recording."""
+    from tests.e2e.pages import HarvestPage
+
+    return HarvestPage(page, base_url)