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/vimade.lua

@@ -1,13 +1,13 @@
 return {
-  "TaDaa/vimade",
-  event = "WinNew",
-  opts = {
-    recipe = { "minimalist", { animate = true } },
-    fadelevel = 0.8,
-    blocklist = {
-      claude_terminal = {
-        buf_opts = { ft = "snacks_terminal" },
-      },
-    },
-  },
+	"TaDaa/vimade",
+	event = "WinNew",
+	opts = {
+		recipe = { "minimalist", { animate = true } },
+		fadelevel = 0.6,
+		blocklist = {
+			claude_terminal = {
+				buf_opts = { ft = "snacks_terminal" },
+			},
+		},
+	},
 }