feat(studio): approval payload — explain absence, cap height, accurate label

The approval card only rendered the payload section when a preview
existed, so a step with no 'show:' showed nothing and the reviewer
could not tell why. Now always show the section: a present payload
scrolls inside a height-capped, copyable box; an absent one shows an
explanatory hint (the flow's approval step chooses what to surface via
its 'show:' field). Relabel 'data to be released' -> 'data to review'
(the payload is review context, accurate to its source).

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/l10n/app_de.arb

@@ -1014,7 +1014,8 @@
   "approvalsPillApproved": "freigegeben",
   "approvalsPillRejected": "abgelehnt",
   "approvalsPillExpired": "abgelaufen",
-  "approvalsPayloadPreview": "DIESE DATEN WERDEN FREIGEGEBEN",
+  "approvalsPayloadPreview": "ZU PRÜFENDE DATEN",
+  "approvalsNoPayload": "Keine Daten zum Prüfen angehängt. Der system.approval-Schritt des Flows bestimmt über sein \"show:\"-Feld, was angezeigt wird — setze es, um die Daten hinter dieser Entscheidung sichtbar zu machen.",
   "approvalsRequestFallback": "Freigabe für diesen Schritt erforderlich",
   "approvalsFlowStepMeta": "Flow: {flow} · Schritt: {step}",
   "approvalsApproveButton": "Freigeben",

lib/l10n/app_en.arb

@@ -1027,7 +1027,8 @@
   "approvalsPillApproved": "approved",
   "approvalsPillRejected": "rejected",
   "approvalsPillExpired": "expired",
-  "approvalsPayloadPreview": "DATA TO BE RELEASED",
+  "approvalsPayloadPreview": "DATA TO REVIEW",
+  "approvalsNoPayload": "No data was attached for review. The flow's approval step chooses what to show via its \"show:\" field — set it to surface the data behind this decision.",
   "approvalsRequestFallback": "Approval required for this step",
   "approvalsFlowStepMeta": "Flow: {flow} · Step: {step}",
   "@approvalsFlowStepMeta": {

lib/l10n/app_localizations.dart

@@ -3065,9 +3065,15 @@ abstract class AppLocalizations {
   /// No description provided for @approvalsPayloadPreview.
   ///
   /// In en, this message translates to:
-  /// **'DATA TO BE RELEASED'**
+  /// **'DATA TO REVIEW'**
   String get approvalsPayloadPreview;
 
+  /// No description provided for @approvalsNoPayload.
+  ///
+  /// In en, this message translates to:
+  /// **'No data was attached for review. The flow\'s approval step chooses what to show via its \"show:\" field — set it to surface the data behind this decision.'**
+  String get approvalsNoPayload;
+
   /// No description provided for @approvalsRequestFallback.
   ///
   /// In en, this message translates to:

lib/l10n/app_localizations_de.dart

@@ -1767,7 +1767,11 @@ class AppLocalizationsDe extends AppLocalizations {
   String get approvalsPillExpired => 'abgelaufen';
 
   @override
-  String get approvalsPayloadPreview => 'DIESE DATEN WERDEN FREIGEGEBEN';
+  String get approvalsPayloadPreview => 'ZU PRÜFENDE DATEN';
+
+  @override
+  String get approvalsNoPayload =>
+      'Keine Daten zum Prüfen angehängt. Der system.approval-Schritt des Flows bestimmt über sein \"show:\"-Feld, was angezeigt wird — setze es, um die Daten hinter dieser Entscheidung sichtbar zu machen.';
 
   @override
   String get approvalsRequestFallback =>

lib/l10n/app_localizations_en.dart

@@ -1777,7 +1777,11 @@ class AppLocalizationsEn extends AppLocalizations {
   String get approvalsPillExpired => 'expired';
 
   @override
-  String get approvalsPayloadPreview => 'DATA TO BE RELEASED';
+  String get approvalsPayloadPreview => 'DATA TO REVIEW';
+
+  @override
+  String get approvalsNoPayload =>
+      'No data was attached for review. The flow\'s approval step chooses what to show via its \"show:\" field — set it to surface the data behind this decision.';
 
   @override
   String get approvalsRequestFallback => 'Approval required for this step';

lib/pages/approvals.dart

@@ -585,7 +585,6 @@ class _ApprovalCard extends StatelessWidget {
               ),
             ],
           ),
-          if (approval.payloadPreview != null) ...[
           const SizedBox(height: ChainSpace.md),
           Padding(
             padding: const EdgeInsets.only(bottom: 4),
@@ -598,14 +597,20 @@ class _ApprovalCard extends StatelessWidget {
               ),
             ),
           ),
+          if (approval.payloadPreview != null)
             Container(
               width: double.infinity,
+              // Cap the height so a large payload scrolls inside the
+              // card instead of stretching it off-screen; still fully
+              // readable + copyable (SelectableText).
+              constraints: const BoxConstraints(maxHeight: 280),
               padding: const EdgeInsets.all(ChainSpace.md),
               decoration: BoxDecoration(
                 color: theme.colorScheme.surfaceContainerHigh,
                 borderRadius: BorderRadius.circular(ChainRadius.sm),
                 border: Border.all(color: theme.colorScheme.outlineVariant),
               ),
+              child: SingleChildScrollView(
                 child: SelectableText(
                   _prettyPreview(approval.payloadPreview!),
                   style: ChainTheme.mono(
@@ -614,7 +619,38 @@ class _ApprovalCard extends StatelessWidget {
                   ),
                 ),
               ),
+            )
+          else
+            // No `show:` on the approval step → explain where the data
+            // would come from instead of rendering nothing.
+            Container(
+              width: double.infinity,
+              padding: const EdgeInsets.all(ChainSpace.md),
+              decoration: BoxDecoration(
+                color: theme.colorScheme.surfaceContainerHigh,
+                borderRadius: BorderRadius.circular(ChainRadius.sm),
+                border: Border.all(color: theme.colorScheme.outlineVariant),
+              ),
+              child: Row(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  Icon(
+                    Icons.info_outline,
+                    size: 14,
+                    color: theme.colorScheme.onSurfaceVariant,
+                  ),
+                  const SizedBox(width: ChainSpace.sm),
+                  Expanded(
+                    child: Text(
+                      l.approvalsNoPayload,
+                      style: theme.textTheme.bodySmall?.copyWith(
+                        color: theme.colorScheme.onSurfaceVariant,
+                      ),
+                    ),
+                  ),
                 ],
+              ),
+            ),
           const SizedBox(height: ChainSpace.lg),
           Row(
             children: [