invite: add proto field (UDP/TCP/BOTH) to invite link binary format

Format per v4 addr: family(1) + socketId(1) + proto(1) + addr(4) + port(2) = 9 bytes (was 8)
Proto values: 0x01=UDP, 0x02=TCP, 0x03=BOTH
Affects: invite_link_c.h/c (Android), invite_link.h/cpp (desktop), chat_sync.c, conn_mgr.c, joindialog.cpp, utun_node.cpp

opencode.json

@@ -0,0 +1,11 @@
+{
+    "$schema": "https://opencode.ai/config.json",
+    "plugin": ["@isac322/kwin-mcp-opencode"],
+    "mcp": {
+        "kwin-mcp": {
+            "type": "local",
+            "command": ["/home/user/.local/bin/uvx", "kwin-mcp"],
+            "enabled": true
+        }
+    }
+}