fix(devtools): compile MCP/AiPanel into existing TUs for MSVC exports

Fold McpServer and AiPanel implementations into DebugAdapter.cpp and
DevTool.cpp via .inc includes so WINDOWS_EXPORT_ALL_SYMBOLS does not add
extra Poco JSON-heavy object files (LNK1189). Keep prior macOS singleton
and ImGui drawer fixes.

Co-authored-by: 西风逍遥游 <sunxfancy@gmail.com>

src/engine/devtools/DebugAdapter.cpp

@@ -668,3 +668,7 @@ bool DebugAdapter::waitUntilConfigured(int timeoutMs) {
 }
 
 }  // namespace eve::dev
+
+// Compile MCP server in this TU so Windows WINDOWS_EXPORT_ALL_SYMBOLS does not
+// grow another object full of Poco JSON template exports (LNK1189).
+#include "devtools/McpServer.inc"