refactor(nvim): modernize plugin stack

Removed dead weight:
- Drop nightfox, rose-pine, kanagawa, everforest colorschemes
- Remove fzf/fzf.vim (redundant with telescope)
- Remove vim-fugitive and its keymaps (lazygit covers this)
- Remove Comment.nvim (built into nvim 0.10+)

Replaced:
- nvim-cmp → blink.cmp (Rust-powered, faster, ghost text)
- none-ls/null-ls → conform.nvim (async, maintained)
- cmp-nvim-lsp capabilities → blink.cmp.get_lsp_capabilities()
- Copilot suggestions now routed through blink-copilot

Added:
- lazydev.nvim for proper Lua LSP in nvim config
- flash.nvim (s/S jump anywhere on screen)
- which-key.nvim (leader key popup with groups)
- snacks.nvim (notifier + word highlights)
- nvim-treesitter-textobjects (af/if, ac/ic, ]f/[f)

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

nvim/lua/plugins/lualine.lua

@@ -188,6 +188,6 @@ return {
     tabline = {},
     winbar = {},
     inactive_winbar = {},
-    extensions = { "nvim-tree", "fzf", "lazy" },
+    extensions = { "nvim-tree", "lazy" },
   },
 }