Phase 5: Compound quantities, trailing-unit format, and edge cases

- Add splitAmountUnit to parse quantities with unit attached without
  % separator (e.g., @water{1,1/2cups}, @gelatine{3tsp})
- Add isNumericChar helper for detecting numeric quantity characters
- Add compound quantity test (1,1/2 cups = 3/2)
- Add no-separator unit test (3tsp)
- All 26 tests passing, all 4 example files parse correctly

test/Roux/ParserSpec.hs

@@ -2,6 +2,7 @@ module Roux.ParserSpec (spec) where
 
 import Data.List.NonEmpty (NonEmpty ((:|)))
 import qualified Data.List.NonEmpty as NE
+import Data.Ratio ((%))
 import qualified Data.Text.IO as TIO
 import Test.Hspec (Spec, describe, expectationFailure, it, shouldBe)
 
@@ -371,6 +372,27 @@ spec = do
                             expectationFailure
                                 ("expected SecStep as third body item, got body=" <> show body)
 
+    describe "Quantities" $ do
+        it "parses compound quantity (1,1/2) with unit attached" $ do
+            let input = "@water{1,1/2cups}"
+            case parseCookFile input of
+                Left err -> expectationFailure ("parse failed: " <> err)
+                Right recipe -> do
+                    let items = stepItems recipe
+                    items
+                        `shouldBe` [ StepIngredient (Ingredient "water" (Just (Quantity (3 % 2) (Just "cups") False)) Nothing)
+                                   ]
+
+        it "parses quantity with trailing unit (no %)" $ do
+            let input = "@gelatine{3tsp}"
+            case parseCookFile input of
+                Left err -> expectationFailure ("parse failed: " <> err)
+                Right recipe -> do
+                    let items = stepItems recipe
+                    items
+                        `shouldBe` [ StepIngredient (Ingredient "gelatine" (Just (Quantity 3 (Just "tsp") False)) Nothing)
+                                   ]
+
     describe "Recipe references" $ do
         it "parses a recipe reference" $ do
             let input = "Pour over with @./sauces/Hollandaise{150%g}."