Integration test fixes: reconcile SyncTypeFlags phantom-bit assertions and sync-round counts

- SyncTypeFlags phantom-bit tests used bits 8/9/10 as unmapped examples;
  board/prekey/group now map those, so use bits 11+ (still unmapped).
- rawValueInitNormalizesPhantomBits: highest known bit is now 10, so the
  flags serialize to 2 bytes, not 1.
- Board/fragment/announce sync tests silence the prekey round (added by the
  prekeys feature; default 60s schedule fires at the maintenance barrier).
- DiagnosticsMockContext: conform to the CommandContextProvider members added
  by private-groups (group*) and cashu-chips (sendPublicMessage).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

bitchatTests/GossipSyncManagerTests.swift

@@ -370,6 +370,8 @@ struct GossipSyncManagerTests {
         config.messageSyncIntervalSeconds = 0
         config.fragmentSyncIntervalSeconds = 0
         config.fileTransferSyncIntervalSeconds = 0
+        // Silence the prekey round so the maintenance barrier below emits nothing.
+        config.prekeyBundleSyncIntervalSeconds = 0
 
         let requestSyncManager = RequestSyncManager()
         let manager = GossipSyncManager(myPeerID: myPeerID, config: config, requestSyncManager: requestSyncManager)
@@ -543,6 +545,8 @@ struct GossipSyncManagerTests {
         config.messageSyncIntervalSeconds = 0
         config.fragmentSyncIntervalSeconds = 0
         config.fileTransferSyncIntervalSeconds = 0
+        // Silence the prekey round so the maintenance barrier isolates fragments.
+        config.prekeyBundleSyncIntervalSeconds = 0
 
         let requestSyncManager = RequestSyncManager()
         let manager = GossipSyncManager(myPeerID: myPeerID, config: config, requestSyncManager: requestSyncManager)