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/trouble.lua

@@ -0,0 +1,18 @@
+vim.pack.add({
+    { src = "https://github.com/folke/trouble.nvim" },
+})
+
+require('trouble').setup({
+    defaults = {
+        auto_close = true,
+        auto_open = true,
+    },
+})
+
+vim.keymap.set('n', "<leader>cx", "<cmd>Trouble diagnostics toggle<cr>", { desc = "Diagnostics (Trouble)" })
+vim.keymap.set('n', "<leader>cX", "<cmd>Trouble diagnostics toggle filter.buf=0<cr>", { desc = "Buffer Diagnostics (Trouble)" })
+vim.keymap.set('n', "<leader>cs", "<cmd>Trouble symbols toggle focus=false<cr>", { desc = "Symbols (Trouble)" })
+vim.keymap.set('n', "<leader>cl", "<cmd>Trouble lsp toggle focus=false win.position=right<cr>", { desc = "LSP Definitions / references / ... (Trouble)" })
+vim.keymap.set('n', "<leader>cL", "<cmd>Trouble loclist toggle<cr>", { desc = "Location List (Trouble)" })
+vim.keymap.set('n', "<leader>cQ", "<cmd>Trouble qflist toggle<cr>", { desc = "Quickfix List (Trouble)" })
+