Replace raw `String(v)` calls with `luaFormatNumber` in the concatenation
operator and `table.concat`, so that floats are formatted according to Lua
semantics rather than JavaScript's. This fixes cases like `10.8*22..""`
producing `237.60000000000002` instead of `237.6`, and ensures
integer-valued floats carry the `.0` suffix as Lua requires.
Signed-off-by: Matouš Jan Fialka <mjf@mjf.cz>