feat(P6/T02-T03): EnvelopeEmissionContract and InteractionReportingContract

T02: EnvelopeEmissionContractsController (index+show, read-only); widgetEnvelope
helper validates against contract v1.0 required attributes with inline warning
on missing view-context; adapterStatusBadge helper added to Application.Helper.View.

T03: InteractionReportingContractsController (index+show, read-only); API endpoint
POST /api/v1/interaction-events with bearer token auth against hub.api_key,
contract v1.0 field validation, and 201/422/401 responses.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Application/Helper/View.hs

@@ -11,6 +11,15 @@ import Web.Types
 -- client-side event capture script reads to identify the widget without coupling
 -- to implementation details.
 --
+-- The envelope is validated against the v1.0 EnvelopeEmissionContract at render
+-- time. Missing required attributes are surfaced as an inline warning banner
+-- (development) rather than a hard failure, so layout is preserved in production.
+--
+-- Required attributes (contract v1.0):
+--   data-widget-id    — stable UUID from the widget registry
+--   data-view-context — logical UI location
+--   data-hub-id       — owning hub UUID
+--
 -- Usage:
 --
 -- @
@@ -18,10 +27,10 @@ import Web.Types
 --     <button>Click me</button>
 -- |]
 -- @
---
--- See docs/widget-envelope-convention.md for the full convention.
 widgetEnvelope :: Widget -> Html -> Html
-widgetEnvelope widget inner = [hsx|
+widgetEnvelope widget inner =
+    let warnings = envelopeContractWarnings widget
+    in [hsx|
     <div
         class="ihf-widget"
         data-widget-id={tshow widget.id}
@@ -32,6 +41,7 @@ widgetEnvelope widget inner = [hsx|
         data-policy-scope={widget.policyScope}
         data-widget-version={tshow widget.version}
     >
+        {renderEnvelopeWarnings warnings}
         {inner}
         <div class="ihf-widget-controls mt-2">
             <a href={WidgetAnnotationsAction { widgetId = widget.id }}
@@ -42,3 +52,32 @@ widgetEnvelope widget inner = [hsx|
         </div>
     </div>
 |]
+
+-- | Validate a Widget record against EnvelopeEmissionContract v1.0 required
+-- attributes. Returns a list of human-readable warning messages for any
+-- attribute that is missing or empty. An empty list means the widget is
+-- contract-compliant.
+envelopeContractWarnings :: Widget -> [Text]
+envelopeContractWarnings widget = catMaybes
+    [ if isNothing widget.viewContext || widget.viewContext == Just ""
+        then Just "envelope:v1.0 — data-view-context is missing (set widget.viewContext)"
+        else Nothing
+    -- data-widget-id and data-hub-id are always present (non-nullable fields)
+    ]
+
+renderEnvelopeWarnings :: [Text] -> Html
+renderEnvelopeWarnings [] = mempty
+renderEnvelopeWarnings ws = [hsx|
+    <div class="bg-amber-50 border border-amber-200 rounded px-3 py-1 mb-1 text-xs text-amber-700">
+        <strong>Envelope contract warning:</strong>
+        {forEach ws (\w -> [hsx|<div>{w}</div>|])}
+    </div>
+|]
+
+-- | Status badge colour for WidgetAdapterSpec and contract status values.
+adapterStatusBadge :: Text -> Text
+adapterStatusBadge "active"     = "bg-green-100 text-green-800"
+adapterStatusBadge "draft"      = "bg-yellow-100 text-yellow-800"
+adapterStatusBadge "deprecated" = "bg-gray-100 text-gray-500"
+adapterStatusBadge "superseded" = "bg-gray-100 text-gray-400"
+adapterStatusBadge _            = "bg-gray-100 text-gray-600"