feat(studio): temporal source bucket + provenance pill on store grid

Adds the missing UI surface for SPARK / Temporal federated
capabilities. Previously only mcp and n8n showed provenance
pills; temporal-sourced entries fell through to the default
"no badge" case.

  - storeSourceTemporal + storeProvenanceTemporal l10n keys
    (en + de). Pill format: "temporal · <provider>", icon
    Icons.timer_outlined, accent tone.
  - Source filter chip row gains a "Temporal" option in the
    Store filter dialog.
  - `_StoreProvenancePill` adds a `case 'temporal'` branch.

Operators federating a SPARK cluster (`services: -
kind: temporal`) now see their workflows visually labelled
as Temporal-sourced in the Store grid + filter UI.

dart analyze green. No test changes required — the
provenance pill is render-only.

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

lib/l10n/app_localizations_de.dart

@@ -2084,4 +2084,12 @@ class AppLocalizationsDe extends AppLocalizations {
   String systemAiPullFailedError(String error) {
     return 'Pull fehlgeschlagen: $error';
   }
+
+  @override
+  String storeProvenanceTemporal(String provider) {
+    return 'temporal · $provider';
+  }
+
+  @override
+  String get storeSourceTemporal => 'Temporal';
 }