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/AgentProposals.hs

@@ -16,8 +16,8 @@ instance Controller AgentProposalsController where
     beforeAction = ensureIsUser
 
     action AgentProposalsAction = do
-        mTypeFilter   <- paramOrNothing @Text "proposal_type"
-        mStatusFilter <- paramOrNothing @Text "status"
+        let mTypeFilter   = paramOrNothing @Text "proposal_type"
+            mStatusFilter = paramOrNothing @Text "status"
         proposals <- case (mTypeFilter, mStatusFilter) of
             (Nothing, Nothing) ->
                 query @AgentProposal |> orderByDesc #createdAt |> fetch
@@ -70,15 +70,15 @@ instance Controller AgentProposalsController where
                 setSuccessMessage "Already reviewed"
                 redirectTo ShowAgentProposalAction { agentProposalId }
             Nothing -> do
-                mUser <- currentUserOrNothing
+                let mUser = currentUserOrNothing
                 let reviewerId = fmap (.id) mUser
                 proposal
                     |> set #status "accepted"
                     |> updateRecord
-                notes <- paramOrNothing @Text "notes"
+                let notes = paramOrNothing @Text "notes"
                 newRecord @AgentReviewRecord
                     |> set #proposalId agentProposalId
-                    |> set #reviewerId (fmap (Id . unId) reviewerId)
+                    |> set #reviewerId (reviewerId)
                     |> set #decision "accepted"
                     |> set #notes notes
                     |> createRecord
@@ -86,20 +86,20 @@ instance Controller AgentProposalsController where
                 when (proposal.proposalType == "requirement_draft") do
                     let mParsed = decode (fromStrict (encodeUtf8 proposal.content))
                                     :: Maybe (HashMap Text Text)
-                    case mParsed of
-                        Just m -> do
+                    case (mParsed, proposal.sourceWidgetId) of
+                        (Just m, Just srcWid) -> do
                             let title = fromMaybe "AI Draft" (HashMap.lookup "title" m)
                                 desc  = fromMaybe ""         (HashMap.lookup "description" m)
                             newRecord @RequirementCandidate
                                 |> set #title title
                                 |> set #description desc
-                                |> set #sourceWidgetId proposal.sourceWidgetId
+                                |> set #sourceWidgetId srcWid
                                 |> set #category "friction"
                                 |> set #status "open"
                                 |> createRecord
                             setSuccessMessage "Requirement candidate created from AI draft"
-                        Nothing ->
-                            setSuccessMessage "Proposal accepted (could not parse JSON for candidate)"
+                        _ ->
+                            setSuccessMessage "Proposal accepted (could not create candidate)"
                 redirectTo ShowAgentProposalAction { agentProposalId }
 
     action RejectProposalAction { agentProposalId } = do
@@ -112,15 +112,15 @@ instance Controller AgentProposalsController where
                 setSuccessMessage "Already reviewed"
                 redirectTo ShowAgentProposalAction { agentProposalId }
             Nothing -> do
-                mUser <- currentUserOrNothing
+                let mUser = currentUserOrNothing
                 let reviewerId = fmap (.id) mUser
                 proposal
                     |> set #status "rejected"
                     |> updateRecord
-                notes <- paramOrNothing @Text "notes"
+                let notes = paramOrNothing @Text "notes"
                 newRecord @AgentReviewRecord
                     |> set #proposalId agentProposalId
-                    |> set #reviewerId (fmap (Id . unId) reviewerId)
+                    |> set #reviewerId (reviewerId)
                     |> set #decision "rejected"
                     |> set #notes notes
                     |> createRecord