Natural ingredient quantity rendering

- showQuantity now produces natural text (4 cups, 125 g, 1/2 tsp)
  instead of Cooklang internal format (4%cup, 125%g, 1/2%tsp)
- Add pluralize helper: cups, tbsp, lbs, pinches, etc.
  Handles common units; unknown units stay unchanged
- Add formatFraction: displays 3/2 as '1 1/2', 1/2 as '1/2'
- No % signs in displayed quantities

src/Roux/Html.hs

@@ -52,16 +52,66 @@ pairWith _ Nothing = Nothing
 pairWith a (Just b) = Just (a, b)
 
 -- | Format a quantity for display.
+-- | Format a quantity for natural display (e.g. @4 cups@, @1/2 tsp@).
 showQuantity :: Quantity -> Text
 showQuantity q =
     let amt = quantityAmount q
         amount = case denominator amt of
             1 -> T.pack (show (numerator amt))
-            _ -> T.pack (show (toDouble amt))
+            _ -> formatFraction amt
         prefix = if quantityFixed q then "=" else ""
-        unit = maybe "" ("%" <>) (quantityUnit q)
+        unit = maybe "" (\u -> " " <> pluralize amt u) (quantityUnit q)
      in prefix <> amount <> unit
 
+-- | Format a rational as a nice fraction string (e.g. @1/2@, @1 1/2@).
+formatFraction :: Rational -> Text
+formatFraction r =
+    let w = numerator r `Prelude.div` denominator r
+        rem = r - toRational w
+     in case w of
+            0 -> simpleFrac rem
+            _ -> T.pack (show w) <> " " <> simpleFrac rem
+  where
+    simpleFrac f =
+        let n = numerator f
+            d = denominator f
+         in T.pack (show n <> "/" <> show d)
+
+-- | Pluralize a unit name based on the amount.
+pluralize :: Rational -> Text -> Text
+pluralize amt unit
+    | amt == 1 = unit
+    | otherwise = case T.toLower unit of
+        -- Units that stay the same (abbreviations, mass, volume)
+        "g" -> "g"
+        "kg" -> "kg"
+        "ml" -> "ml"
+        "l" -> "l"
+        "oz" -> "oz"
+        "lb" -> "lbs"
+        "tbsp" -> "tbsp"
+        "tsp" -> "tsp"
+        "cup" -> "cups"
+        "tablespoon" -> "tablespoons"
+        "teaspoon" -> "teaspoons"
+        "ounce" -> "ounces"
+        "pound" -> "pounds"
+        "pinch" -> "pinches"
+        "clove" -> "cloves"
+        "item" -> "items"
+        "piece" -> "pieces"
+        "can" -> "cans"
+        "package" -> "packages"
+        "bag" -> "bags"
+        "bunch" -> "bunches"
+        "sprig" -> "sprigs"
+        "leaf" -> "leaves"
+        "slice" -> "slices"
+        "minute" -> "minutes"
+        "hour" -> "hours"
+        "second" -> "seconds"
+        _ -> unit
+
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 -- Page shell
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