fix(WP-0017/E3): Layer 3 error fixes — controllers and views

Fix compilation errors across 6 controllers and 29 views: import cleanup,
ResponseException pattern for API auth, type fixes, unused import removal.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Web/Controller/Api/V2/Auth.hs

@@ -10,6 +10,7 @@ import qualified Data.Text.Encoding as TE
 import qualified "cryptohash-sha256" Crypto.Hash.SHA256 as SHA256
 import qualified Data.ByteString.Base16 as Base16
 import Network.Wai (requestHeaders, responseLBS)
+import IHP.Controller.Response (ResponseException (..))
 
 -- | Extract Bearer token from Authorization header and validate it
 -- against the api_keys table. Returns the ApiConsumer on success,
@@ -52,12 +53,10 @@ unauthorized401 = respondWithStatus 401 $ object
     ]
 
 respondWithStatus :: (?respond :: Respond) => Int -> Value -> IO a
-respondWithStatus status body = do
-    respondAndExit $ responseLBS
-        (toEnum status)
-        [("Content-Type", "application/json")]
-        (encode body)
-    error "respondAndExit: unreachable"
+respondWithStatus status body = throwIO $ ResponseException $ responseLBS
+    (toEnum status)
+    [("Content-Type", "application/json")]
+    (encode body)
 
 -- | SHA-256 hex hash of the key (same as stored in key_hash column)
 hashApiKey :: Text -> Text