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/CDClientTables/CDZoneTableTable.cpp

@@ -1,8 +1,17 @@
 #include "CDZoneTableTable.h"
 
+#include <memory>
+#include <vector>
+
 namespace CDZoneTableTable {
 	Table entries;
 
+	void Reset() {
+		static std::vector<std::unique_ptr<Table>> retired;
+		retired.push_back(std::make_unique<Table>(std::move(entries)));
+		entries = {};
+	}
+
 	void LoadValuesFromDatabase() {
 		// Get the data from the database
 		auto tableData = CDClientDatabase::ExecuteQuery("SELECT * FROM ZoneTable");

dDatabase/CDClientDatabase/CDClientTables/CDZoneTableTable.h

@@ -37,6 +37,9 @@ namespace CDZoneTableTable {
 	using Table = std::map<uint32_t, CDZoneTable>;
 	void LoadValuesFromDatabase();
 
+	// Empties the table for a CDClient reload. The old entries are kept alive, so a pointer from Query stays valid
+	void Reset();
+
 	// Queries the table with a zoneID to find.
 	const CDZoneTable* Query(uint32_t zoneID);
 };