feat: add scoreboard with player names, per-category leaderboards, and themed tables

Add player_name column to games (migration included), with regex-based
validation and anti-abuse sanitization. New /scoreboard page shows recent
games from localStorage, popular categories with play counts, and top-10
per-category leaderboards sorted by completion time. Also includes
two-click reverse word matching, base URL prefix support for reverse-proxy
hosting, BasePageHandler refactoring, themed table CSS for all 5 themes,
and comprehensive test coverage for player names and scoreboard API.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/e2e/test_api.py

@@ -258,3 +258,101 @@ async def test_guess_cells_with_null_element(http_server_client, seeded_db):
     assert resp.code == 200
     data = json.loads(resp.body)
     assert data["correct"] is False
+
+
+async def test_new_game_with_player_name(http_server_client, seeded_db):
+    body = json.dumps(
+        {"category_id": seeded_db.id, "board_size": 10, "player_name": "Alice"}
+    )
+    resp = await http_server_client.fetch(
+        "/api/game/new",
+        method="POST",
+        body=body,
+        headers={"Content-Type": "application/json"},
+    )
+    assert resp.code == 200
+    data = json.loads(resp.body)
+    assert data["player_name"] == "Alice"
+
+
+async def test_new_game_default_player_name(http_server_client, seeded_db):
+    body = json.dumps({"category_id": seeded_db.id, "board_size": 10})
+    resp = await http_server_client.fetch(
+        "/api/game/new",
+        method="POST",
+        body=body,
+        headers={"Content-Type": "application/json"},
+    )
+    assert resp.code == 200
+    data = json.loads(resp.body)
+    assert data["player_name"] == "Anonymous"
+
+
+async def test_new_game_invalid_player_name_chars(http_server_client, seeded_db):
+    body = json.dumps(
+        {"category_id": seeded_db.id, "player_name": "<script>alert(1)</script>"}
+    )
+    resp = await http_server_client.fetch(
+        "/api/game/new",
+        method="POST",
+        body=body,
+        headers={"Content-Type": "application/json"},
+        raise_error=False,
+    )
+    assert resp.code == 400
+    data = json.loads(resp.body)
+    assert "error" in data
+
+
+async def test_scoreboard_empty(http_server_client, seeded_db):
+    resp = await http_server_client.fetch("/api/scoreboard")
+    assert resp.code == 200
+    data = json.loads(resp.body)
+    assert data["leaderboards"] == {}
+    assert isinstance(data["popular_categories"], list)
+
+
+async def test_scoreboard_with_completed_game(http_server_client, seeded_db):
+    # Create a game with few words so we can complete it
+    body = json.dumps(
+        {
+            "category_id": seeded_db.id,
+            "board_size": 10,
+            "word_count": 3,
+            "player_name": "TestPlayer",
+        }
+    )
+    create_resp = await http_server_client.fetch(
+        "/api/game/new",
+        method="POST",
+        body=body,
+        headers={"Content-Type": "application/json"},
+    )
+    game_data = json.loads(create_resp.body)
+    game_id = game_data["id"]
+
+    # Find all words by text guess
+    for w in game_data["words"]:
+        guess_body = json.dumps({"word": w["text"]})
+        resp = await http_server_client.fetch(
+            f"/api/game/{game_id}/guess",
+            method="POST",
+            body=guess_body,
+            headers={"Content-Type": "application/json"},
+        )
+        assert resp.code == 200
+
+    # Verify game is completed
+    state_resp = await http_server_client.fetch(f"/api/game/{game_id}")
+    state_data = json.loads(state_resp.body)
+    assert state_data["status"] == "completed"
+
+    # Now check scoreboard
+    sb_resp = await http_server_client.fetch("/api/scoreboard")
+    assert sb_resp.code == 200
+    sb_data = json.loads(sb_resp.body)
+    assert "animals" in sb_data["leaderboards"]
+    entry = sb_data["leaderboards"]["animals"][0]
+    assert entry["player_name"] == "TestPlayer"
+    assert entry["time_seconds"] >= 0
+    assert entry["board_size"] == 10

tests/e2e/test_hello.py

@@ -0,0 +1,33 @@
+import pytest
+
+from app import make_app
+
+
+@pytest.fixture
+def app():
+    return make_app()
+
+
+async def test_homepage_returns_200(http_server_client):
+    response = await http_server_client.fetch("/")
+    assert response.code == 200
+
+
+async def test_game_returns_200(http_server_client):
+    response = await http_server_client.fetch("/game")
+    assert response.code == 200
+
+
+async def test_howtoplay_returns_200(http_server_client):
+    response = await http_server_client.fetch("/howtoplay")
+    assert response.code == 200
+
+
+async def test_about_returns_200(http_server_client):
+    response = await http_server_client.fetch("/about")
+    assert response.code == 200
+
+
+async def test_scoreboard_returns_200(http_server_client):
+    response = await http_server_client.fetch("/scoreboard")
+    assert response.code == 200