fix(BUG-4): updateDoc patch on activeDisplay (not setDoc replace)

All 5 storage.setDoc(activeDisplay, {...}, {merge:true}) →
storage.updateDoc(activeDisplay, {...}).

setDoc merge:true worked in prod (firebase honors merge) but ws adapter
+ mock ignore opts arg entirely → clobbers doc. updateDoc uses PATCH
across all adapters (firebase real updateDoc, ws PATCH endpoint, mock
merge). Consistent, no clobber.

Sites fixed:
- hidePlayerHp toggle
- startEncounter (set active ids)
- endEncounter (null active ids)
- deactivate active display
- activate new display

TDD: HideHpToggle.test RED first (assert updateDoc patch, impl still
setDoc → 0 calls found). GREEN after switch.

Char tests updated: Encounter.characterization (2) + Combat.characterization
(2) assert updateDoc on activeDisplay, not setDoc.

BUG-4: prod was already fixed (merge:true), test was RED due to mock
ignoring opts. Now all 3 adapters consistent via updateDoc.

src/tests/Encounter.characterization.test.js

@@ -42,7 +42,7 @@ describe('Encounter -> Firebase', () => {
     expect(call.path).toMatch(/campaigns\/[^/]+\/encounters\//);
   });
 
-  test('togglePlayerDisplay: setDoc merge on activeDisplay/status', async () => {
+  test('togglePlayerDisplay: updateDoc patch on activeDisplay/status', async () => {
     await setupCampaignAndEncounter('Camp D', 'Enc D');
     await selectEncounterByName('Enc D');
 
@@ -50,33 +50,33 @@ describe('Encounter -> Firebase', () => {
     const eyeBtn = await screen.findByTitle('Activate for Player Display');
     fireEvent.click(eyeBtn);
 
-    await waitFor(() => findCall('setDoc', 'activeDisplay/status'));
-    const call = findCall('setDoc', 'activeDisplay/status');
-    // activeDisplay/status setDoc is called with merge option in App
+    await waitFor(() => findCall('updateDoc', 'activeDisplay/status'));
+    const call = findCall('updateDoc', 'activeDisplay/status');
+    // BUG-4 fix: updateDoc patch, not setDoc replace (was clobbering fields)
     expect(call.data).toMatchObject({
       activeCampaignId: expect.any(String),
       activeEncounterId: expect.any(String),
     });
   });
 
-  test('togglePlayerDisplay off: setDoc nulls active ids', async () => {
+  test('togglePlayerDisplay off: updateDoc nulls active ids', async () => {
     await setupCampaignAndEncounter('Camp O', 'Enc O');
     await selectEncounterByName('Enc O');
 
     // turn ON
     const onBtn = await screen.findByTitle('Activate for Player Display');
     fireEvent.click(onBtn);
-    await waitFor(() => findCall('setDoc', 'activeDisplay/status'));
+    await waitFor(() => findCall('updateDoc', 'activeDisplay/status'));
 
     // turn OFF
     const offBtn = await screen.findByTitle('Deactivate for Player Display');
     fireEvent.click(offBtn);
     await waitFor(() => {
-      const calls = findCalls('setDoc', 'activeDisplay/status');
+      const calls = findCalls('updateDoc', 'activeDisplay/status');
       const last = calls[calls.length - 1];
       return last.data.activeCampaignId === null;
     });
-    const calls = findCalls('setDoc', 'activeDisplay/status');
+    const calls = findCalls('updateDoc', 'activeDisplay/status');
     const last = calls[calls.length - 1];
     expect(last.data).toMatchObject({ activeCampaignId: null, activeEncounterId: null });
   });
@@ -103,7 +103,7 @@ describe('Encounter -> Firebase', () => {
     // activate display first
     const onBtn = await screen.findByTitle('Activate for Player Display');
     fireEvent.click(onBtn);
-    await waitFor(() => findCall('setDoc', 'activeDisplay/status'));
+    await waitFor(() => findCall('updateDoc', 'activeDisplay/status'));
 
     // delete the active encounter
     const trashBtn = screen.getAllByTitle('Delete Encounter')[0];