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/AgentDelegations.hs

@@ -31,9 +31,9 @@ instance Controller AgentDelegationsController where
 
     action DelegateSubtaskAction { agentProposalId } = do
         proposal <- fetch agentProposalId
-        receivingAgentId <- param @(Id AgentRegistration) "receivingAgentId"
-        scope            <- param @Text "scope"
-        tokenBudget      <- paramOrDefault @Int 1000 "tokenBudget"
+        let receivingAgentId = param @(Id AgentRegistration) "receivingAgentId"
+            scope            = param @Text "scope"
+            tokenBudget      = paramOrDefault @Int 1000 "tokenBudget"
         delegatingAgentId <- case proposal.agentRegistrationId of
             Just aid -> pure aid
             Nothing  -> respondAndExit =<< renderNotFound