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/testing.lua

@@ -0,0 +1,33 @@
+return {
+  {
+    "nvim-neotest/neotest",
+    dependencies = {
+      "nvim-lua/plenary.nvim",
+      "nvim-treesitter/nvim-treesitter",
+      "nvim-neotest/nvim-nio",
+      "rouge8/neotest-rust",
+      "rcasia/neotest-java",
+    },
+    keys = {
+      { "<leader>tr", function() require("neotest").run.run() end,                           desc = "Run nearest test"  },
+      { "<leader>ts", function() require("neotest").run.run(vim.fn.expand("%")) end,         desc = "Run test suite"    },
+      { "<leader>tl", function() require("neotest").run.run_last() end,                      desc = "Run last test"     },
+      { "<leader>to", function() require("neotest").output.open({ enter = true }) end,       desc = "Open test output"  },
+      { "<leader>tp", function() require("neotest").output_panel.toggle() end,               desc = "Toggle test panel" },
+      { "<leader>ts", function() require("neotest").summary.toggle() end,                    desc = "Toggle summary"    },
+    },
+    opts = function()
+      return {
+        adapters = {
+          require("neotest-rust")({ args = { "--no-capture" } }),
+          require("neotest-java")({
+            ignore_wrapper = false,
+          }),
+        },
+        output = { open_on_run = false },
+        quickfix = { open = false },
+        status = { virtual_text = true },
+      }
+    end,
+  },
+}