showNumberImpl uses Lua tostring — wrong format vs PureScript show (0.0, NaN, Infinity, exponents)

[Unisay]

Data/Show.lua showNumberImpl = tostring, but Lua 5.1 tostring does not match PureScript/JS show :: Number -> String:

value	PureScript show	Lua tostring
0.0	0.0	0
500.0	500.0	500
1e10	10000000000.0	10000000000
1/0	Infinity	inf
-1/0	-Infinity	-inf
0/0	NaN	-nan

So integral Numbers lose the .0, and infinities/NaN print Lua spellings. This is the same class as the showString/showArray FFI divergences. It blocks reviving the upstream testNumberShow suite (test/Test/Main.purs), which asserts the PureScript formats.

Fix needs a formatter that adds .0 for integral finite numbers and maps inf/nan to Infinity/-Infinity/NaN (mirroring the upstream JS show). Found while reviving the prelude test suite (closes-with-credit of #2 by @UnrelatedString).

[Unisay]

Fixed in v7.3.0: showNumberImpl emits NaN/Infinity/-Infinity and a trailing .0 on integral Numbers. Verified under Lua 5.1.