feat(cdclient): make a new CDServer.sqlite off-thread and swap tables in place

CDClientSnapshot converts a copy of the client's fdb into its own
CDServer-<hash>.sqlite with the cdserver migrations applied, on its own
connection. CDClientDatabase::Reconnect opens the new file before letting go
of the old one; CDClientManager::Reload empties every table (old entries kept
alive so references from spawned objects stay valid), retires the old fdb view
and loads again.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dDatabase/CDClientDatabase/CDClientDatabase.h

@@ -26,6 +26,12 @@ namespace CDClientDatabase {
 	 */
 	void Connect(const std::string& filename);
 
+	/**
+	 * Switches to another CDServer.sqlite (a CDClient reload, see FdbSnapshot.h). The new file is opened before the
+	 * old connection is let go; throws CppSQLite3Exception and keeps the old one if it can't be opened.
+	 */
+	void Reconnect(const std::string& filename);
+
 	//! Queries the CDClient
 	/*!
 	  \param query The query