feat(next-gen): onboarding (existing seedphrase)

[meeh0w]

⚠️ Based on #264
⚠️ No worries, plenty of added lines is due to the SVG images included (over 40 avatars). Feel free to focus on reviewing from the 2nd commit onwards.

Description

• CP-10576

Changes

• Adds a bunch of avatar SVGs
• Adds the common screens (choice between seedphrase/ledger/keystone + wallet details form + avatar selector + success screen)
• Adds the whole recovery phrase import flow
• I removed the mocky Onboarding.test.tsx file, because it was failing due to some Jest config stuff I didn't want to focus on at the moment (importing images).

Testing

• Clear your storage
• Onboard with existing seedphrase
• After onboarding, you should see the "Under construction" text

Screenshots:

Screen.Recording.2025-05-23.at.23.15.31.mov

Checklist for the author

• I've covered new/modified business logic with Jest test cases.
• I've tested the changes myself before sending it to code review and QA.

[semgrep-code-ava-labs]

Semgrep found 2 ssc-b5cd4801-a3c5-43d5-bca5-c7fdef10f97b findings:

• packages/service-worker/src/services/featureFlags/FeatureFlagService.ts
  • L76 - Triage
  • L83 - Triage

Risk: Affected versions of semver are vulnerable to Inefficient Regular Expression Complexity. The vulnerability exists in the package semver allowing Regular Expression Denial of Service (ReDoS) through the new Range when untrusted user data is input as a range.

Fix: Upgrade this library to at least version 7.5.2 at core-extension/yarn.lock:30864.

Reference(s): GHSA-c2qf-rxjj-qqgw, CVE-2022-25883