fix(WP-0016): Layer 3 compilation fixes — Sessions auth, Widgets import consolidation, Scientific type

- Sessions: replace raw authenticate/unsetSession with IHP login/logout/verifyPassword
- Widgets/New, Widgets/Show: consolidate imports to Web.View.Prelude
- Widgets/Show: unwrap Id newtype for childrenOf comparison, Double → Scientific in renderSignalValue

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

Web/View/Widgets/New.hs

@@ -1,10 +1,6 @@
 module Web.View.Widgets.New where
 
-import Web.Types
-import Generated.Types
-import IHP.Prelude
-import IHP.ViewPrelude
-import Web.Routes ()
+import Web.View.Prelude
 
 data NewView = NewView
     { widget       :: !Widget

Web/View/Widgets/Show.hs

@@ -1,10 +1,7 @@
 module Web.View.Widgets.Show where
 
-import Web.Types
-import Generated.Types
-import IHP.Prelude
-import IHP.ViewPrelude
-import Web.Routes ()
+import Web.View.Prelude
+import Data.Scientific (Scientific)
 import Application.Helper.View (widgetEnvelope)
 
 data ShowView = ShowView
@@ -135,7 +132,7 @@ instance View ShowView where
             </div>
             |]
         rootAnnotations = filter (\a -> isNothing a.parentId) annotations
-        childrenOf parent = filter (\a -> a.parentId == Just parent.id) annotations
+        childrenOf parent = filter (\a -> a.parentId == Just (let Id uuid = parent.id in uuid)) annotations
         categoryBreakdown =
             [ (cat, length (filter (\a -> a.category == cat) annotations))
             | cat <- ["friction","defect","wish","policy_concern","doc_gap","trust","other"]
@@ -241,7 +238,7 @@ renderSignalsSection sigs = [hsx|
     </section>
 |]
 
-renderSignalValue :: Double -> Html
+renderSignalValue :: Scientific -> Html
 renderSignalValue v = [hsx|<span class="font-mono text-gray-700">{show v}</span>|]
 
 renderAdapterBadge :: Maybe WidgetAdapterSpec -> Html