refactor: move sqlite3 db from topo_group to UTUN_INSTANCE, remove conn_mgr/topo_group deps from chatgui

- topo_sqlite_db moved from TOPO_GROUPS to UTUN_INSTANCE (direct access)
- topo_groups_set_sqlite_db() removed
- chatgui: chat_sync_connect_node → chat_core_connect_auto (direct ETCP, no conn_mgr)
- chatgui: chat_core_connect_from_invite saves to SQLite → auto connect (no BGP)
- chatgui: removed _on_node_updated BGP callback from member_sync
- chatgui: removed conn_mgr_get_status from status dump
- chatgui: removed all conn_mgr.h and topo_group.h includes
- chatgui: CONN_MGR_ERR_* constants → CC_* in chat_core.h
- removed unused cc_parallel_* code, conn_state_str/conn_type_str helpers

src/utun_instance.h

@@ -10,6 +10,7 @@ extern "C" {
 #include <stdbool.h>
 #include <stdio.h>
 #include "../lib/memory_pool.h"
+#include "../lib/sqlite3.h"
 #include "secure_channel.h"
 #include "etcp_api.h"
 #include "config_parser.h"
@@ -75,6 +76,7 @@ struct UTUN_INSTANCE {
 
     struct ROUTE_TABLE* rt;
     struct TOPO_GROUPS* topo_groups;    // Groups module for topology exchange
+    sqlite3* topo_sqlite_db;            // Shared SQLite DB (nodes/channels/peers)
     struct NAT_DETECTION* nat_det;      // NAT detection module
     
     // Identification