test: warning=failure guard + fix ambiguous switch selector

- setupTests.js: console.error/warn now throw. Warning = failure.
- Combat.characterization: two role=switch (player HP + NPC HP), scope
  to player-HP label. getByRole('switch') was ambiguous.

Full suite: 77/77 pass, 0 warnings.

src/tests/Combat.characterization.test.js

@@ -123,7 +123,9 @@ describe('Combat -> Firebase', () => {
   test('toggleHidePlayerHp: updateDoc patch on activeDisplay/status', async () => {
     await setupWithMonsters();
     await startCombatViaUI();
-    const switchBtn = screen.getByRole('switch');
+    // Two switches now (Hide player HP + Hide NPC/monster HP). Scope to player one.
+    const playerHpLabel = screen.getByText('Hide player HP');
+    const switchBtn = playerHpLabel.parentElement.querySelector('[role="switch"]');
     fireEvent.click(switchBtn);
     await waitFor(() => {
       const adCalls = findCallActiveDisplay('updateDoc');