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/CollectiveProposals.hs

@@ -30,12 +30,12 @@ instance Controller CollectiveProposalsController where
         render ShowView { proposal, agentContributions = agentNames }
 
     action CreateCollectiveProposalAction = do
-        hubId    <- param @(Id Hub) "hubId"
-        title    <- param @Text "title"
-        taskType <- param @Text "taskType"
-        prompt   <- param @Text "prompt"
-        mWidgetId <- paramOrNothing @(Id Widget) "sourceWidgetId"
-        mCandId   <- paramOrNothing @(Id RequirementCandidate) "sourceCandidateId"
+        let hubId    = param @(Id Hub) "hubId"
+            title    = param @Text "title"
+            taskType = param @Text "taskType"
+            prompt   = param @Text "prompt"
+            mWidgetId = paramOrNothing @(Id Widget) "sourceWidgetId"
+            mCandId   = paramOrNothing @(Id RequirementCandidate) "sourceCandidateId"
 
         proposal <- newRecord @CollectiveProposal
             |> set #title title