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/TypeRegistries.hs

@@ -68,7 +68,7 @@ instance Controller TypeRegistriesController where
 
     action DeprecateWidgetTypeAction { widgetTypeRegistryId } = do
         entry <- fetch widgetTypeRegistryId
-        replacedBy <- param @Text "deprecated_in_favour_of"
+        let replacedBy = param @Text "deprecated_in_favour_of"
         when (null replacedBy) do
             setErrorMessage "You must specify the replacement type name"
             redirectTo WidgetTypeRegistryAction
@@ -134,7 +134,7 @@ instance Controller TypeRegistriesController where
 
     action DeprecateEventTypeAction { eventTypeRegistryId } = do
         entry <- fetch eventTypeRegistryId
-        replacedBy <- param @Text "deprecated_in_favour_of"
+        let replacedBy = param @Text "deprecated_in_favour_of"
         when (null replacedBy) do
             setErrorMessage "You must specify the replacement type name"
             redirectTo EventTypeRegistryAction
@@ -200,7 +200,7 @@ instance Controller TypeRegistriesController where
 
     action DeprecateAnnotationCategoryAction { annotationCategoryRegistryId } = do
         entry <- fetch annotationCategoryRegistryId
-        replacedBy <- param @Text "deprecated_in_favour_of"
+        let replacedBy = param @Text "deprecated_in_favour_of"
         when (null replacedBy) do
             setErrorMessage "You must specify the replacement category name"
             redirectTo AnnotationCategoryRegistryAction
@@ -266,7 +266,7 @@ instance Controller TypeRegistriesController where
 
     action DeprecatePolicyScopeAction { policyScopeRegistryId } = do
         entry <- fetch policyScopeRegistryId
-        replacedBy <- param @Text "deprecated_in_favour_of"
+        let replacedBy = param @Text "deprecated_in_favour_of"
         when (null replacedBy) do
             setErrorMessage "You must specify the replacement scope name"
             redirectTo PolicyScopeRegistryAction