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/just.lua

@@ -0,0 +1,14 @@
+if vim.fn.executable("just") == 1 then
+    vim.pack.add({ { src = 'https://github.com/al1-ce/just.nvim' } })
+
+    require("just").setup({
+        fidget_message_limit = 32, -- limit for length of fidget progress message
+        open_qf_on_error = true,   -- opens quickfix when task fails
+        open_qf_on_run = true,     -- opens quickfix when running `run` task (`:JustRun`)
+        open_qf_on_any = false;    -- opens quickfix when running any task (overrides other open_qf options)
+        autoscroll_qf = true,      -- automatically scroll quickfix window on output
+        register_commands = true,  -- if set to true then commands (:Just*) will be registered
+        notify = vim.notify,       -- what to use to show messages/errors
+    })
+end
+