Implement onboarding reset functionality and enhance backup features

- Added a new method to reset the onboarding state, allowing users to re-initiate the onboarding process.
- Integrated backup creation functionality, enabling users to create encrypted backups of their node identity.
- Updated API endpoints to handle onboarding reset and backup creation requests.
- Enhanced UI components to support the new onboarding reset and backup features, including error handling and user feedback.
- Introduced new dependencies for cryptographic operations and data encoding.

core/archipelago/src/auth.rs

@@ -86,6 +86,24 @@ impl AuthManager {
         Ok(())
     }
 
+    /// Reset onboarding state so the user can go through onboarding again (dev/testing).
+    pub async fn reset_onboarding(&self) -> Result<()> {
+        let onboarding_file = self.data_dir.join("onboarding.json");
+        let state = OnboardingState { complete: false };
+        fs::write(
+            &onboarding_file,
+            serde_json::to_string_pretty(&state)?,
+        )
+        .await?;
+        if let Some(mut user) = self.get_user().await? {
+            user.onboarding_complete = false;
+            let user_file = self.data_dir.join("user.json");
+            let content = serde_json::to_string_pretty(&user)?;
+            fs::write(&user_file, content).await?;
+        }
+        Ok(())
+    }
+
     pub async fn is_onboarding_complete(&self) -> Result<bool> {
         // Check onboarding.json first (persisted before user setup)
         let onboarding_file = self.data_dir.join("onboarding.json");