fix(math): fix build error, add missing tests, fix CHANGELOG order

Replace IEnumerable<T> with seq<T> in fsum/prod to fix build (missing
import). Add tests for nan, prod, perm, dist, hyperbolic functions,
and special functions. Move Unreleased section above rc.3 in CHANGELOG.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: dbrattli

CHANGELOG.md

@@ -7,12 +7,6 @@ name: Fable.Python
 
 All notable changes to this project will be documented in this file.
 
-## 5.0.0-rc.3 - 2026-04-16
-
-### 🐞 Bug Fixes
-
-* Bump Fable.Core to 5.0.0-rc.2 and ShipIt to 2.0.2 (#243) ([cb06fd6](https://github.com/fable-compiler/Fable.Python/commit/cb06fd6fc338fde73e8eb3c3720ed20bfdd17287))
-
 ## Unreleased
 
 ### 🐞 Bug Fixes
@@ -25,6 +19,12 @@ All notable changes to this project will be documented in this file.
 * Add missing `math` module functions: `sqrt`, `degrees`, `radians`, `trunc`, `hypot`, `fsum`, `isqrt`, `prod`, `perm`, `acosh`, `asinh`, `atanh`, `cosh`, `sinh`, `tanh`, `erf`, `erfc`, `gamma`, `lgamma`
 * Fix `math.dist` signature to accept float arrays (for multi-dimensional distance)
 
+## 5.0.0-rc.3 - 2026-04-16
+
+### 🐞 Bug Fixes
+
+* Bump Fable.Core to 5.0.0-rc.2 and ShipIt to 2.0.2 (#243) ([cb06fd6](https://github.com/fable-compiler/Fable.Python/commit/cb06fd6fc338fde73e8eb3c3720ed20bfdd17287))
+
 <strong><small>[View changes on Github](https://github.com/fable-compiler/Fable.Python/compare/8223cc8eb8b2dcaa02c1a19566c5ed5d73242b11..66e56764fefe824e1b2a28635245820c2dc92a34)</small></strong>
 
 ## 5.0.0-rc.2 - 2026-03-09

src/stdlib/Math.fs

@@ -62,7 +62,7 @@ type IExports =
     abstract fmod: x: int -> y: int -> int
     /// Return an accurate floating-point sum of values in the iterable
     /// See https://docs.python.org/3/library/math.html#math.fsum
-    abstract fsum: iterable: IEnumerable<float> -> float
+    abstract fsum: iterable: float seq -> float
     /// Return the greatest common divisor of the integers
     /// See https://docs.python.org/3/library/math.html#math.gcd
     abstract gcd: [<ParamArray>] ints: int[] -> int
@@ -80,7 +80,7 @@ type IExports =
     abstract perm: n: int * k: int -> int
     /// Return the product of all elements in the iterable
     /// See https://docs.python.org/3/library/math.html#math.prod
-    abstract prod: iterable: IEnumerable<'T> -> 'T
+    abstract prod: iterable: 'T seq -> 'T
     /// Truncate x to an integer (towards zero)
     /// See https://docs.python.org/3/library/math.html#math.trunc
     abstract trunc: x: float -> int

test/TestMath.fs

@@ -166,3 +166,61 @@ let ``test isqrt works`` () =
 [<Fact>]
 let ``test fsum works`` () =
     math.fsum [ 1.0; 2.0; 3.0 ] |> equal 6.0
+
+[<Fact>]
+let ``test nan constant works`` () =
+    math.isnan math.nan |> equal true
+
+[<Fact>]
+let ``test prod works`` () =
+    math.prod [ 1; 2; 3; 4 ] |> equal 24
+
+[<Fact>]
+let ``test perm works`` () =
+    math.perm 5 |> equal 120
+    math.perm (5, 2) |> equal 20
+
+[<Fact>]
+let ``test dist works`` () =
+    math.dist [| 0.0; 0.0 |] [| 3.0; 4.0 |] |> equal 5.0
+
+[<Fact>]
+let ``test cosh works`` () =
+    math.cosh 0.0 |> equal 1.0
+
+[<Fact>]
+let ``test sinh works`` () =
+    math.sinh 0.0 |> equal 0.0
+
+[<Fact>]
+let ``test tanh works`` () =
+    math.tanh 0.0 |> equal 0.0
+
+[<Fact>]
+let ``test acosh works`` () =
+    math.acosh 1.0 |> equal 0.0
+
+[<Fact>]
+let ``test asinh works`` () =
+    math.asinh 0.0 |> equal 0.0
+
+[<Fact>]
+let ``test atanh works`` () =
+    math.atanh 0.0 |> equal 0.0
+
+[<Fact>]
+let ``test erf works`` () =
+    math.erf 0.0 |> equal 0.0
+
+[<Fact>]
+let ``test erfc works`` () =
+    math.erfc 0.0 |> equal 1.0
+
+[<Fact>]
+let ``test gamma works`` () =
+    math.gamma 1.0 |> equal 1.0
+    math.gamma 5.0 |> equal 24.0
+
+[<Fact>]
+let ``test lgamma works`` () =
+    math.lgamma 1.0 |> equal 0.0