chore: remove dead config and test residue

- inlay_hints = { enable = true } on lua_ls and solidity_ls: nothing in
  nvim's LSP core reads that key. vim.lsp.inlay_hint.enable() already
  turns them on.
- commented-out wgsl_analyzer block
- <leader>rn in on_attach: mappings.lua already binds it globally to the
  same vim.lsp.buf.rename
- mini.files enabled = false: NvChad does not ship it, so there was
  nothing to disable. The nvim-tree stub stays; that one is real.
- biome.json and .tool-versions: no JS in this repo

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

lua/plugins/file-explorer.lua

@@ -1,10 +1,7 @@
 return {
+  -- shipped by NvChad; disabled in favour of yazi (see plugins/yazi.lua)
   {
     "nvim-tree/nvim-tree.lua",
     enabled = false,
   },
-  {
-    "echasnovski/mini.files",
-    enabled = false,
-  },
 }