Update nvim config: switch to tab indentation, update claudecode and vimade settings

Remove stylua.toml (was enforcing 2-space indent), add tab settings in options.lua,
update claudecode.nvim terminal/diff config, lower vimade fadelevel to 0.6, remove
claudecode LazyExtra in favor of custom plugin spec, and add .luarc.json.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

nvim/lua/plugins/snacks.lua

@@ -1,13 +1,13 @@
 return {
-  {
-    "snacks.nvim",
-    opts = {
-      dashboard = {
-        preset = {
-          pick = function(cmd, opts)
-            return LazyVim.pick(cmd, opts)()
-          end,
-          header = [[
+	{
+		"snacks.nvim",
+		opts = {
+			dashboard = {
+				preset = {
+					pick = function(cmd, opts)
+						return LazyVim.pick(cmd, opts)()
+					end,
+					header = [[
           ███████╗████████╗██████╗ 
           ██╔════╝╚══██╔══╝██╔══██╗
           ███████╗   ██║   ██████╔╝
@@ -16,7 +16,6 @@ return {
           ╚══════╝   ╚═╝   ╚═╝     
   ]],
           -- stylua: ignore
-          ---@type snacks.dashboard.Item[]
           keys = {
             { icon = " ", key = "f", desc = "Find File", action = ":lua Snacks.dashboard.pick('files')" },
             { icon = " ", key = "n", desc = "New File", action = ":ene | startinsert" },
@@ -28,8 +27,8 @@ return {
             { icon = "󰒲 ", key = "l", desc = "Lazy", action = ":Lazy" },
             { icon = " ", key = "q", desc = "Quit", action = ":qa" },
           },
-        },
-      },
-    },
-  },
+				},
+			},
+		},
+	},
 }