[neovim] Add MCPHub integration

Enhance snacks plugin configuration by adding:
- MCPHub integration with dedicated menu entry
- Explorer configuration for picker with hidden and ignored files
  enabled

.config/nvim/lua/plugins/init.lua

@@ -1,6 +1,7 @@
 require("plugins.snacks")
 require("plugins.blink")
 require("plugins.copilot")
+require("plugins.mcphub")
 require("plugins.avante")
 require("plugins.telescope")
 require("plugins.mini-comment")