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/after/queries/jinja/injections.scm

@@ -0,0 +1,6 @@
+; Jinja template injection queries
+; Injects HTML into Jinja host language nodes
+
+((text) @injection.content
+ (#set! injection.language "html")
+ (#set! injection.combined))