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/lsp/lua_ls.lua

@@ -0,0 +1,17 @@
+vim.lsp.config("lua_ls", {
+  settings = {
+    Lua = {
+      runtime = { version = "LuaJIT" },
+      workspace = {
+        checkThirdParty = false,
+        library = {
+          vim.env.VIMRUNTIME,
+          "${3rd}/luv/library",
+        },
+      },
+      diagnostics = { globals = { "vim" } },
+      telemetry = { enable = false },
+      format = { enable = false }, -- stylua handles formatting
+    },
+  },
+})