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.

lazy-lock.json

@@ -8,7 +8,6 @@
   "cmp-path": { "branch": "main", "commit": "c642487086dbd9a93160e1679a1327be111cbc25" },
   "cmp_luasnip": { "branch": "master", "commit": "98d9cb5c2c38532bd9bdb481067b20fea8f32e90" },
   "conform.nvim": { "branch": "master", "commit": "dca1a190aa85f9065979ef35802fb77131911106" },
-  "dressing.nvim": { "branch": "master", "commit": "2d7c2db2507fa3c4956142ee607431ddb2828639" },
   "flash.nvim": { "branch": "main", "commit": "3c942666f115e2811e959eabbdd361a025db8b63" },
   "flutter-tools.nvim": { "branch": "main", "commit": "70430c32d176f4a15c6e2c80586cd2791e3a664e" },
   "friendly-snippets": { "branch": "main", "commit": "6cd7280adead7f586db6fccbd15d2cac7e2188b9" },
@@ -37,7 +36,6 @@
   "nvim-lsp-file-operations": { "branch": "master", "commit": "b9c795d3973e8eec22706af14959bc60c579e771" },
   "nvim-lspconfig": { "branch": "master", "commit": "31026a13eefb20681124706a79fc1df6bf11ab27" },
   "nvim-nio": { "branch": "master", "commit": "21f5324bfac14e22ba26553caf69ec76ae8a7662" },
-  "nvim-notify": { "branch": "master", "commit": "8701bece920b38ea289b457f902e2ad184131a5d" },
   "nvim-silicon": { "branch": "main", "commit": "7f66bda8f60c97a5bf4b37e5b8acb0e829ae3c32" },
   "nvim-surround": { "branch": "main", "commit": "ae298105122c87bbe0a36b1ad20b06d417c0433e" },
   "nvim-tmux-navigation": { "branch": "main", "commit": "4898c98702954439233fdaf764c39636681e2861" },