refactor(config/nvim): move pack.add declarations into individual plugin files

The monolithic vim.pack.add() table in init.lua was removed and each
plugin/*.lua file now declares its own dependencies via vim.pack.add()
at the top. tools.lua was decomposed into per-plugin files (cmake.lua,
jupynvim.lua, just.lua, kulala.lua, mise.lua, neogit.lua, sshfs.lua,
trouble.lua, undotree.lua, zoxide.lua) each with their own config and
keymaps. This makes plugin files self-contained and easier to maintain.

config/nvim/plugin/lsp.lua

@@ -1,3 +1,13 @@
+vim.pack.add({
+    { src = 'https://github.com/williamboman/mason-lspconfig.nvim' },
+    { src = 'https://github.com/williamboman/mason.nvim' },
+    { src = 'https://github.com/neovim/nvim-lspconfig' },
+    { src = 'https://github.com/rcarriga/nvim-dap-ui' },
+    { src = 'https://github.com/mfussenegger/nvim-dap' },
+    { src = 'https://github.com/jay-babu/mason-nvim-dap.nvim' },
+    { src = 'https://github.com/WhoIsSethDaniel/mason-tool-installer.nvim' },
+})
+
 vim.keymap.set("i", "<C-.>", function()
     if not vim.lsp.inline_completion.get() then
         return "<C-.>"