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/views/ContactsView.vue

@@ -168,6 +168,7 @@ import {
   NOTIFY_CONTACT_INVALID_DID,
   NOTIFY_CONTACTS_ADDED_VISIBLE,
   NOTIFY_CONTACTS_ADDED,
+  NOTIFY_CONTACTS_ADDED_CONFIRM,
   NOTIFY_CONTACT_IMPORT_ERROR,
   NOTIFY_CONTACT_IMPORT_CONFLICT,
   NOTIFY_CONTACT_IMPORT_CONSTRAINT,
@@ -328,8 +329,11 @@ export default class ContactsView extends Vue {
       // this happens when a platform (eg iOS) doesn't include anything after the "=" in a shared link.
       this.notify.error(NOTIFY_BLANK_INVITE.message, TIMEOUTS.VERY_LONG);
     } else if (importedInviteJwt) {
-      // make sure user is created
+      // Identity creation should be handled by router guard, but keep as fallback for invite processing
       if (!this.activeDid) {
+        logger.info(
+          "[ContactsView] No active DID found, creating identity as fallback for invite processing",
+        );
         this.activeDid = await generateSaveAndActivateIdentity();
       }
       // send invite directly to server, with auth for this user
@@ -408,15 +412,10 @@ export default class ContactsView extends Vue {
   // Legacy danger() and warning() methods removed - now using this.notify.error() and this.notify.warning()
 
   private showOnboardingInfo() {
-    this.$notify(
-      {
-        group: "modal",
-        type: "confirm",
-        title: "They're Added To Your List",
-        text: "Would you like to go to the main page now?",
-        onYes: async () => {
-          this.$router.push({ name: "home" });
-        },
+    this.notify.confirm(
+      NOTIFY_CONTACTS_ADDED_CONFIRM.message,
+      async () => {
+        this.$router.push({ name: "home" });
       },
       -1,
     );