refactor: separate plugins and settings into modular structure

[Henrik-Wik]

Summary

• Extract vim settings to plugin/options.lua
• Extract keymaps and autocmds to plugin/keymaps.lua
• Extract plugin specs into lua/plugins/ (one file per plugin)
• Simplify init.lua to just bootstrap lazy.nvim with import
• Follow tjdevries/config.nvim structure

Changes

• Added plugin/options.lua - vim settings (leader, clipboard, ui options)
• Added plugin/keymaps.lua - global keymaps and diagnostic config
• Added lua/plugins/ - 13 plugin spec files extracted from init.lua
• Simplified init.lua (~30 lines) - only bootstraps lazy.nvim

Structure

init.lua                    (root - bootstraps lazy.nvim)
plugin/                     (auto-loaded by Neovim)
├── options.lua
├── keymaps.lua
lua/plugins/                (lazy.nvim plugin specs)
├── init.lua
├── lsp.lua
├── telescope.lua
├── completion.lua
├── formatting.lua
├── treesitter.lua
├── colorscheme.lua
├── mini.lua
├── gitsigns.lua
├── oil.lua
├── which-key.lua
├── todo-comments.lua
└── guess-indent.lua

[szechp]

you do know of the existence of https://github.com/dam9000/kickstart-modular.nvim, right?

[Henrik-Wik]

Oh no I didn't haha, thanks! I meant to create this PR on my personal fork ofc, but I had forgotten to change the remote 😅