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/View/AdaptiveThresholds/Index.hs

@@ -37,7 +37,6 @@ instance View IndexView where
                         {renderCfgStatus mCfg}
                     </div>
                     <form method="POST" action={CalibrateThresholdsAction (h.id)}>
-                        {csrfTokenTag}
                         <button type="submit"
                             class="px-3 py-1.5 text-sm bg-indigo-600 text-white rounded hover:bg-indigo-700">
                             Calibrate