refactor: integer functions, optimize asserts #34112

refactor(lua): add integer coercion helpers

Add vim._tointeger() and vim._ensure_integer(), including optional base
support, and switch integer-only tonumber()/assert call sites in the Lua
runtime to use them.

This also cleans up related integer parsing in LSP, health, loader, URI,
tohtml, and Treesitter code.

supported by AI

runtime/lua/vim/pack/_lsp.lua

@@ -20,7 +20,7 @@ function methods.shutdown(_, callback)
 end
 
 local get_confirm_bufnr = function(uri)
-  return tonumber(uri:match('^nvim%-pack://confirm#(%d+)$'))
+  return vim._tointeger(uri:match('^nvim%-pack://confirm#(%d+)$'))
 end
 
 local group_header_pattern = '^# (%S+)'