fix: properly percent-decode URL-encoded form values in import

The urldecode helper in parseFormBody was using Html.urlDecode which only
handled %%20, %%23, and %%25. Full URLs encode colons, slashes, and dots
as %%3A, %%2F, and %%2E, so they were never decoded. The scraper received
the still-encoded URL and failed to fetch it.

Replace Html.urlDecode with a proper percent-decode that handles all %%XX
hex sequences using digitToInt.

src/Roux/Server.hs

@@ -17,7 +17,7 @@ import Control.Monad (forM_, forever, when)
 import Data.ByteString.Builder (lazyByteString)
 import Data.ByteString.Lazy (ByteString)
 import qualified Data.ByteString.Lazy as LB
-import Data.Char (toLower)
+import Data.Char (digitToInt, toLower)
 import Data.IORef (IORef, atomicModifyIORef', newIORef, readIORef, writeIORef)
 import Data.List (isSuffixOf)
 import Data.Map.Strict (Map)
@@ -226,7 +226,13 @@ parseFormBody body =
     parsePair part = case T.splitOn "=" part of
         [key, val] -> Just (urldecode key, urldecode val)
         _ -> Nothing
-    urldecode = T.pack . Html.urlDecode . T.replace "+" " "
+    -- Proper percent-decode for all %XX sequences (not just %20/%23/%25).
+    urldecode = T.pack . go . T.unpack . T.replace "+" " "
+    go [] = []
+    go ('%' : a : b : rest) =
+        let hexVal = digitToInt a * 16 + digitToInt b
+         in toEnum hexVal : go rest
+    go (c : rest) = c : go rest
 
 -- | Locate the scrape-recipe script: check PATH first, then relative to project.
 findScrapeScript :: IO FilePath