match main firebase behavior; fix contract + mismatches

Contract rewritten to match main prod truth:
- require id injection in all doc/collection results
- honor setDoc({merge:true}) (main L1624 + 4 activeDisplay sites)
- drop invented bare<->prefixed cross-lookup tests (main never does this)
- add setDoc{merge}, batch set-only/update-only contract coverage

Fix mismatches vs main:
- subscribeCollection hook now forwards queryConstraints (was dropped;
  LOG_QUERY sort+limit honored again). Mock onSnapshot honors orderBy+limit.
  2 new contract tests prove the chain.
- subscribeDoc/subscribeCollection adapters now forward errCb. App hooks +
  DisplayView propagate subscribe errors to UI (match main onSnapshot 3rd arg).
- ws adapter signatures accept queryConstraints + errCb (interface match).

activeDisplay writes match main:
- 5 unguarded sites -> setDoc({merge:true}) (create-if-missing, not updateDoc)
- 3 guarded sites stay updateDoc

Delete memory adapter: third storage system added complexity, zero value.
firebase-mock covers fast tests, ws covers server path. Factory throws on
unknown mode now.

Delete phantom 'Phase A/B' comment in firebase.js header.

Tests updated to assert setDoc{merge} (not updateDoc) for activeDisplay writes.
83/83 green.

src/tests/Combat.characterization.test.js

@@ -41,7 +41,7 @@ describe('Combat -> Firebase', () => {
   test('startEncounter: also sets activeDisplay to this encounter', async () => {
     await setupWithMonsters();
     await startCombatViaUI();
-    const adCalls = findCallActiveDisplay('updateDoc');
+    const adCalls = findCallActiveDisplay('setDoc');
     const last = adCalls[adCalls.length - 1];
     expect(last.data.activeCampaignId).toBeTruthy();
     expect(last.data.activeEncounterId).toBeTruthy();
@@ -111,16 +111,16 @@ describe('Combat -> Firebase', () => {
     fireEvent.click(screen.getByRole('button', { name: /End Combat/i }));
     fireEvent.click(await screen.findByRole('button', { name: /Confirm/i }));
     await waitFor(() => {
-      const adCalls = findCallActiveDisplay('updateDoc');
+      const adCalls = findCallActiveDisplay('setDoc');
       const last = adCalls[adCalls.length - 1];
       return last && last.data.activeCampaignId === null;
     });
-    const adCalls = findCallActiveDisplay('updateDoc');
+    const adCalls = findCallActiveDisplay('setDoc');
     const last = adCalls[adCalls.length - 1];
     expect(last.data).toMatchObject({ activeCampaignId: null, activeEncounterId: null });
   });
 
-  test('toggleHidePlayerHp: updateDoc patch on activeDisplay/status', async () => {
+  test('toggleHidePlayerHp: setDoc{merge} patch on activeDisplay/status', async () => {
     await setupWithMonsters();
     await startCombatViaUI();
     // Two switches now (Hide player HP + Hide NPC/monster HP). Scope to player one.
@@ -128,11 +128,11 @@ describe('Combat -> Firebase', () => {
     const switchBtn = playerHpLabel.parentElement.querySelector('[role="switch"]');
     fireEvent.click(switchBtn);
     await waitFor(() => {
-      const adCalls = findCallActiveDisplay('updateDoc');
+      const adCalls = findCallActiveDisplay('setDoc');
       const last = adCalls[adCalls.length - 1];
       return last && 'hidePlayerHp' in last.data;
     });
-    const adCalls = findCallActiveDisplay('updateDoc');
+    const adCalls = findCallActiveDisplay('setDoc');
     const last = adCalls[adCalls.length - 1];
     expect(last.data).toHaveProperty('hidePlayerHp');
   });