feat(nvim): phase 2 — replace nvim-notify and dressing with snacks

Enable snacks.input and snacks.notifier modules; remove the
now-redundant nvim-notify and archived dressing.nvim specs.
Notifier preserves the prior icons and 3000 ms timeout.

lua/absolute/after/notify.lua

@@ -1,25 +0,0 @@
-local notify = require("notify")
-
-notify.setup({
-	background_colour = "#000000",
-	fps = 15,
-	icons = {
-		DEBUG = "",
-		ERROR = "",
-		INFO = "",
-		TRACE = "✎",
-		WARN = "",
-	},
-	level = 2,
-	minimum_width = 50,
-	render = "default",
-	stages = "static",
-	time_formats = {
-		notification = "%T",
-		notification_history = "%FT%T",
-	},
-	timeout = 3000,
-	top_down = true,
-})
-
-vim.notify = notify