fix(store,audit,workspace): usertest low-findings tail (0.72.1)

- Store hero: 'TODAY' badge only for an operator-accepted story; the
  rotating compiled-in fallback deck now says 'FEATURED' (no false
  freshness claim). Policy as a top-level function with unit tests.
- Audit filter chips: standard label typography instead of mono —
  mono stays reserved for paths and identifiers.
- DE chain wording: 'Hash-Kette geprüft' as the one confirmation term
  (audit header now matches the doctor pill); 'intakt' stays the
  state headline. EN was already consistent.
- Workspace switcher: contrast bump for the sealed-area 'stopped'
  label.

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

lib/widgets/chain_workspace_switcher.dart

@@ -149,9 +149,12 @@ class ChainWorkspaceSwitcher extends StatelessWidget {
                         ? l.workspaceSealedRunning
                         : l.workspaceSealedStopped,
                     style: theme.textTheme.labelSmall?.copyWith(
+                      // Secondary but readable — onSurfaceVariant
+                      // fell below comfortable contrast at this
+                      // size (usertest finding).
                       color: a.running
                           ? ChainColors.success
-                          : theme.colorScheme.onSurfaceVariant,
+                          : theme.colorScheme.onSurface.withValues(alpha: 0.8),
                     ),
                   ),
                 ),