Optimize Neovim configuration structure and LSP setup

- Remove duplicate nvim-web-devicons loading (already in kickstart)
- Add clangd configuration to custom LSP setup with proper flags
- Replace complex clangd_helper with universal LSP reload keybind (<leader>lr)
- Clean up unused clangd target selection keybind
- Streamline plugin organization for better maintainability

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

lua/custom/plugins/lsp/init.lua

@@ -1,4 +1,3 @@
 return {
   require 'custom.plugins.lsp.lsp',
-  require 'custom.plugins.lsp.clangd',
 }