fix(WP-0014/A2): close remaining pure-param and structural compilation errors

Convert all remaining `<- paramOrNothing / param / paramOrDefault /
currentUserOrNothing` monadic binds to `let` — these functions are pure
(ImplicitParams-based) in IHP v1.5, so `<-` is a type error in an IO
do-block.

Controllers fixed:
  AgentDelegations, AiGovernancePolicies, Annotations, ApiConsumers,
  CollectiveProposals, DecisionRecords, DeploymentRecords,
  HubCapabilityManifests, HubRoutingRules, InstitutionalKnowledge,
  OutcomeCorrelations, RequirementCandidates, TypeRegistries,
  WebhookSubscriptions, Widgets,
  Api/V2/{Annotations,InteractionEvents,Token}

WebhookSubscriptions: remove orphaned `Right () ->` case arm that was
left inside a bare `unless` block (structural parse error).

Also carries forward all in-progress fixes from the working tree:
  helpers (AgentBridge, ApiRateLimit, BottleneckDetector,
            CrossHubPropagation, FrictionScore),
  views (CanSelect instances, HSX lambda extraction, formFor wrappers),
  env/build (envrc GHCi perms, flake.nix Tailwind + GHC resource limits,
             static/app.css additional Tailwind output).

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

Web/Controller/Annotations.hs

@@ -41,11 +41,10 @@ instance Controller AnnotationsController where
     action CreateAnnotationAction { widgetId } = do
         widget     <- fetch widgetId
         categories <- activeAnnotationCategories
-        mUser      <- currentUserOrNothing
-        let actorId   = fmap (.id) mUser
+        let mUser     = currentUserOrNothing
+            actorId   = fmap (.id) mUser
             actorType = maybe "anonymous" (const "user") mUser
-
-        category <- paramOrDefault @Text "" "category"
+            category  = paramOrDefault @Text "" "category"
         categoryResult <- validateAnnotationCategory category
 
         let annotation = newRecord @Annotation
@@ -68,8 +67,8 @@ instance Controller AnnotationsController where
 
     action EscalateAnnotationAction { annotationId } = do
         annotation <- fetch annotationId
-        mUser      <- currentUserOrNothing
-        let createdBy = fmap (.id) mUser
+        let mUser     = currentUserOrNothing
+            createdBy = fmap (.id) mUser
         -- Idempotent: check if already escalated
         existing <- query @RequirementCandidate
             |> filterWhere (#sourceAnnotationId, Just annotationId)