fix: use got_initial_pkt instead of new_conn for send_reset decision

new_conn is only true for the first INIT after server restart.
Subsequent INITs from same peer (recovery loop) see new_conn=0
and revert to old logic, sending 0x05 (no reset) and overwriting
the first 0x03 response.

got_initial_pkt stays 0 until client actually sends seq=1, so
server keeps sending 0x03 across all INIT retries until client
resets and starts from seq=1.

src/etcp_connections.c

@@ -1727,9 +1727,9 @@ void etcp_connections_read_callback_socket(socket_t sock, void* arg) {
         // For CHANNEL_INIT (0x04): if link already initialized - no reset, otherwise reset
         // For INIT_REQUEST (0x02): always reset
         // Check session_id: if same - no reinit, if different - client restarted, do reinit
-        if (code == ETCP_INIT_REQUEST || conn->session_id != session_id || new_conn) {
-            send_reset = 1;  // Client explicitly requested reset, or new session, or new server-side connection
-            DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "do reinit (code=%02x session was %08x now %08x new_conn=%d)", code, conn->session_id, session_id, new_conn);
+        if (code == ETCP_INIT_REQUEST || conn->session_id != session_id || !conn->got_initial_pkt) {
+            send_reset = 1;  // Client explicitly requested reset, or new session, or server waiting for first packet
+            DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "do reinit (code=%02x session was %08x now %08x got_init=%d)", code, conn->session_id, session_id, conn->got_initial_pkt);
             conn->session_id = session_id;
             etcp_conn_reinit(conn);
         } else {
@@ -1753,9 +1753,9 @@ void etcp_connections_read_callback_socket(socket_t sock, void* arg) {
         link->remote_type = req->type;
 
         // For new links: reset if client requested or session changed
-        if (code == ETCP_INIT_REQUEST || conn->session_id != session_id || new_conn) {
+        if (code == ETCP_INIT_REQUEST || conn->session_id != session_id || !conn->got_initial_pkt) {
             send_reset = 1;
-            DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "do reinit for new link (code=%02x session was %08x now %08x new_conn=%d)", code, conn->session_id, session_id, new_conn);
+            DEBUG_TRACE(DEBUG_CATEGORY_CONNECTION, "do reinit for new link (code=%02x session was %08x now %08x got_init=%d)", code, conn->session_id, session_id, conn->got_initial_pkt);
             conn->session_id = session_id;
             etcp_conn_reinit(conn);
         }