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/apex-neon.lua

@@ -0,0 +1,10 @@
+-- Proxy so require("apex-neon") returns the colorscheme module
+-- colors/apex-neon.lua is managed by refresh-apex-themes — do not edit that file
+-- This shim is safe to keep in chezmoi alongside the colors/ file
+local colors_path = vim.fn.stdpath("config") .. "/colors/apex-neon.lua"
+local ok, result = pcall(dofile, colors_path)
+if not ok then
+  vim.notify("apex-neon shim: failed to load " .. colors_path, vim.log.levels.WARN)
+  return {}
+end
+return result