nvim,tmux,kitty: full config overhaul (AstroNvim → native 0.12)

Replaces AstroNvim v5 with from-scratch Neovim 0.12 config using
vim.lsp.config()/vim.lsp.enable() natively, lazy.nvim, blink.cmp,
and smart-splits tmux integration.

tmux: new C-Space prefix, hjkl pane nav, resize key table, tpm plugins.
kitty: add allow_remote_control for smart-splits.

dot_config/nvim/lua/plugins/latex-snippets.lua

@@ -1,17 +1,2 @@
--- Gilles Castel-style LaTeX snippets for LuaSnip
-return {
-  -- Make sure autosnippets are enabled globally
-  {
-    "L3MON4D3/LuaSnip",
-    opts = function(_, opts) opts.enable_autosnippets = true end,
-  },
-
-  -- The LaTeX snippets themselves
-  {
-    "iurimateus/luasnip-latex-snippets.nvim",
-    ft = { "tex", "plaintex", "markdown" },
-    dependencies = { "L3MON4D3/LuaSnip", "lervag/vimtex" },
-    opts = { use_treesitter = false, allow_on_markdown = true }, -- use vimtex to detect math mode
-    config = function(_, opts) require("luasnip-latex-snippets").setup(opts) end,
-  },
-}
+-- luasnip-latex-snippets is configured in completion.lua
+return {}