feat: migrate TopMessage.vue to use new ActiveDid pattern

Replace `settings.activeDid` with `$getActiveIdentity()` API call.
Updates test/prod server warning logic to use active_identity table.

- Add `const activeIdentity = await this.$getActiveIdentity();`
- Update didPrefix extraction for both warning conditions
- Maintain existing warning functionality

✅ TypeScript compilation passes
✅ Linting standards met
✅ Functionality preserved

Part of ActiveDid migration following "One Component + Test Pattern".

src/components/TopMessage.vue

@@ -49,8 +49,11 @@ export default class TopMessage extends Vue {
       logger.debug("[TopMessage] 📥 Loading settings without overrides...");
       const settings = await this.$accountSettings();
 
+      // Get activeDid from new active_identity table (ActiveDid migration)
+      const activeIdentity = await this.$getActiveIdentity();
+
       logger.debug("[TopMessage] 📊 Settings loaded:", {
-        activeDid: settings.activeDid,
+        activeDid: activeIdentity.activeDid,
         apiServer: settings.apiServer,
         warnIfTestServer: settings.warnIfTestServer,
         warnIfProdServer: settings.warnIfProdServer,
@@ -64,7 +67,7 @@ export default class TopMessage extends Vue {
         settings.apiServer &&
         settings.apiServer !== AppString.PROD_ENDORSER_API_SERVER
       ) {
-        const didPrefix = settings.activeDid?.slice(11, 15);
+        const didPrefix = activeIdentity.activeDid?.slice(11, 15);
         this.message = "You're not using prod, user " + didPrefix;
         logger.debug("[TopMessage] ⚠️ Test server warning displayed:", {
           apiServer: settings.apiServer,
@@ -75,7 +78,7 @@ export default class TopMessage extends Vue {
         settings.apiServer &&
         settings.apiServer === AppString.PROD_ENDORSER_API_SERVER
       ) {
-        const didPrefix = settings.activeDid?.slice(11, 15);
+        const didPrefix = activeIdentity.activeDid?.slice(11, 15);
         this.message = "You are using prod, user " + didPrefix;
         logger.debug("[TopMessage] ⚠️ Production server warning displayed:", {
           apiServer: settings.apiServer,