feat: centralize identity creation with router navigation guard

Migrate automatic identity creation from scattered view components to centralized
router navigation guard for consistent behavior across all entry points.

**Key Changes:**
- Add global beforeEach navigation guard in router/index.ts
- Remove automatic identity creation from HomeView, ContactsView, InviteOneAcceptView,
  and OnboardMeetingMembersView
- Keep minimal fallback logic in deep link scenarios with logging
- Exclude manual identity creation routes (/start, /new-identifier, /import-account)

**Benefits:**
- Eliminates code duplication and race conditions
- Ensures consistent identity creation regardless of entry point
- Centralizes error handling with fallback to manual creation
- Improves maintainability with single point of change

**Files Modified:**
- src/router/index.ts: Add navigation guard with identity creation logic
- src/views/HomeView.vue: Remove automatic creation, simplify initializeIdentity()
- src/views/ContactsView.vue: Add fallback with logging
- src/views/InviteOneAcceptView.vue: Add fallback with logging
- src/views/OnboardMeetingMembersView.vue: Add fallback with logging

**Testing:**
- Verified first-time user navigation creates identity automatically
- Confirmed existing users bypass creation logic
- Validated manual creation routes remain unaffected
- Tested deep link scenarios with fallback logic

**Documentation:**
- Created docs/identity-creation-migration.md with comprehensive details
- Includes migration rationale, implementation details, testing scenarios
- Documents security considerations and rollback plan

Resolves inconsistent identity creation behavior across different app entry points.

src/router/index.ts

@@ -6,6 +6,10 @@ import {
   RouteRecordRaw,
 } from "vue-router";
 import { logger } from "../utils/logger";
+import {
+  retrieveAccountDids,
+  generateSaveAndActivateIdentity,
+} from "../libs/util";
 
 const routes: Array<RouteRecordRaw> = [
   {
@@ -316,6 +320,65 @@ const errorHandler = (
 
 router.onError(errorHandler); // Assign the error handler to the router instance
 
+/**
+ * Global navigation guard to ensure user identity exists
+ *
+ * This guard checks if the user has any identities before navigating to most routes.
+ * If no identity exists, it automatically creates one using the default seed-based method.
+ *
+ * Routes that are excluded from this check:
+ * - /start - Manual identity creation selection
+ * - /new-identifier - Manual seed-based creation
+ * - /import-account - Manual import flow
+ * - /import-derive - Manual derivation flow
+ * - /database-migration - Migration utilities
+ * - /deep-link-error - Error page
+ *
+ * @param to - Target route
+ * @param from - Source route
+ * @param next - Navigation function
+ */
+router.beforeEach(async (to, from, next) => {
+  try {
+    // Skip identity check for routes that handle identity creation manually
+    const skipIdentityRoutes = [
+      "/start",
+      "/new-identifier",
+      "/import-account",
+      "/import-derive",
+      "/database-migration",
+      "/deep-link-error",
+    ];
+
+    if (skipIdentityRoutes.includes(to.path)) {
+      return next();
+    }
+
+    // Check if user has any identities
+    const allMyDids = await retrieveAccountDids();
+
+    if (allMyDids.length === 0) {
+      logger.info("[Router] No identities found, creating default identity");
+
+      // Create identity automatically using seed-based method
+      await generateSaveAndActivateIdentity();
+
+      logger.info("[Router] Default identity created successfully");
+    }
+
+    next();
+  } catch (error) {
+    logger.error(
+      "[Router] Identity creation failed in navigation guard:",
+      error,
+    );
+
+    // Redirect to start page if identity creation fails
+    // This allows users to manually create an identity or troubleshoot
+    next("/start");
+  }
+});
+
 // router.beforeEach((to, from, next) => {
 //   console.log("Navigating to view:", to.name);
 //   console.log("From view:", from.name);