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/Api/V2/Widgets.hs

@@ -12,12 +12,12 @@ instance Controller ApiV2WidgetsController where
     action ApiV2IndexWidgetsAction = do
         _consumer <- requireApiConsumer
         (page, perPage) <- getPageParams
-        let offset = (page - 1) * perPage
+        let pageOffset = (page - 1) * perPage
         total   <- query @Widget |> fetchCount
         widgets <- query @Widget
             |> orderByDesc #createdAt
             |> limit perPage
-            |> offset offset
+            |> offset pageOffset
             |> fetch
         renderJson $ paginatedResponse (map widgetToJson widgets) page perPage total