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/Auth.hs

@@ -57,6 +57,7 @@ respondWithStatus status body = do
         (toEnum status)
         [("Content-Type", "application/json")]
         (encode body)
+    error "respondAndExit: unreachable"
 
 -- | SHA-256 hex hash of the key (same as stored in key_hash column)
 hashApiKey :: Text -> Text
@@ -78,10 +79,10 @@ paginatedResponse items page perPage total =
         ]
 
 -- | Parse page / per_page query params with sensible defaults
-getPageParams :: (?context :: ControllerContext) => IO (Int, Int)
+getPageParams :: (?context :: ControllerContext, ?request :: Request) => IO (Int, Int)
 getPageParams = do
-    page    <- fromMaybe 1   <$> paramOrNothing @Int "page"
-    perPage <- fromMaybe 50  <$> paramOrNothing @Int "per_page"
+    let page    = fromMaybe 1  (paramOrNothing @Int "page")
+        perPage = fromMaybe 50 (paramOrNothing @Int "per_page")
     let perPage' = min 200 (max 1 perPage)
     let page'    = max 1 page
     pure (page', perPage')