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/yamlls.lua

@@ -0,0 +1,11 @@
+vim.lsp.config("yamlls", {
+  settings = {
+    yaml = {
+      keyOrdering = false,
+      format = { enable = true },
+      validate = true,
+      schemaStore = { enable = false, url = "" },
+      schemas = {},
+    },
+  },
+})