Swap the completion engine to blink.cmp v1.x, dropping nvim-cmp,
its eight cmp-* sources, lspkind, and LuaSnip. Swap the picker
to snacks.picker, removing telescope.nvim and six telescope
extensions. LSP capabilities now sourced from blink.cmp; LSP
navigation keymaps and the colorscheme/keymaps/todo pickers move
to Snacks.picker. friendly-snippets is preserved as blink's
snippet source.
Fix keymap collision on <leader>j/<leader>k (now resize-only;
location-list moved to ]l/[l). Migrate diagnostic signs from
deprecated vim.fn.sign_define to vim.diagnostic.config. Drop
orphan after/nvim-tree.lua and the bogus require("../current-theme").
Add foundation snacks.nvim spec. Remove playground, vim-maximizer,
poet-v, git-blame, render-markdown, and all five AI plugin specs.
Enable gitsigns current_line_blame.