Fix all hlint warnings

- Html.hs: replace lambdas with section/composition where possible
- Html.hs: replace case/fromMaybe with fromMaybe
- Html.hs: add fromMaybe to imports, use unqualified
- Parser.hs: replace span with break (2 locations)
- Parser.hs: replace if/then/else with list comprehension
- Parser.hs: remove redundant catch-all patterns (break is exhaustive)
- Server.hs: eta reduce htmlResponse
- Add .hlint.yaml to suppress 'Avoid lambda' (suggested fix has
  precedence issues with blaze-html's infix (!) operator)
- All 26 tests passing, hlint: No hints, exit code 0

src/Roux/Html.hs

@@ -18,7 +18,7 @@ import Control.Monad (unless)
 import Data.ByteString.Lazy (ByteString)
 import Data.Function ((&))
 import qualified Data.List.NonEmpty as NE
-import Data.Maybe (catMaybes)
+import Data.Maybe (catMaybes, fromMaybe)
 import Data.Ratio (denominator, numerator)
 import Data.Text (Text)
 import qualified Data.Text as T
@@ -46,7 +46,7 @@ showQuantity q =
             1 -> T.pack (show (numerator amt))
             _ -> T.pack (show (toDouble amt))
         prefix = if quantityFixed q then "=" else ""
-        unit = maybe "" (\u -> "%" <> u) (quantityUnit q)
+        unit = maybe "" ("%" <>) (quantityUnit q)
      in prefix <> amount <> unit
 
 -- ---------------------------------------------------------------------------
@@ -93,7 +93,7 @@ indexPage recipes =
         let bad = filter (isLeft . Idx.riRecipe) recipes
         unless (null bad) $ do
             H.h3 "Unparseable recipes"
-            H.ul $ mapM_ (\r -> H.li $ H.toHtml (Idx.riTitle r)) bad
+            H.ul $ mapM_ (H.li . H.toHtml . Idx.riTitle) bad
 
 -- | Render a single recipe link on the index page.
 recipeItem :: FilePath -> Html
@@ -134,10 +134,7 @@ renderRecipe recipe = do
 
 -- | Extract display title from recipe metadata or fallback.
 titleText :: Recipe -> Text
-titleText recipe =
-    case metaTitle (recipeMetadata recipe) of
-        Just t -> t
-        Nothing -> "Untitled Recipe"
+titleText recipe = fromMaybe "Untitled Recipe" (metaTitle (recipeMetadata recipe))
 
 -- ---------------------------------------------------------------------------
 -- Metadata
@@ -179,7 +176,7 @@ showDuration d =
         amount = case denominator amt of
             1 -> T.pack (show (numerator amt))
             _ -> T.pack (show (toDouble amt))
-        unit = maybe "" Prelude.id (durationUnit d)
+        unit = fromMaybe "" (durationUnit d)
      in T.strip (amount <> " " <> unit)
 
 -- | Roughly convert Rational to Double for display.