[FE-50] Build KYC verification UI — document submission and status tracking for investors

[yusuftomilola]

Overview

Before a user can acquire tokens in a tokenized asset, they must pass KYC (Know Your Customer) verification. This UI allows users to submit their KYC documents and track their verification status. Depends on BE-64 for the API.

Context

• Add KYC section to the user settings page (frontend/app/(dashboard)/settings/page.tsx)
• API endpoints (from BE-64): POST /stellar/kyc/submit, GET /stellar/kyc/status
• KYC status: PENDING, VERIFIED, REJECTED

Acceptance Criteria

• Add a "KYC Verification" section to the Settings page
• Status display: shows current KYC status with appropriate colour (grey=NOT_SUBMITTED, yellow=PENDING, green=VERIFIED, red=REJECTED)
• If NOT_SUBMITTED: show a "Submit KYC" button that opens a form: document type (PASSPORT, NATIONAL_ID, DRIVERS_LICENSE), document number, country of issue, expiry date
• Document upload: React Dropzone for uploading a photo/scan of the document (front and back if applicable)
• If PENDING: show "Your documents are under review. This typically takes 1–2 business days."
• If REJECTED: show the rejection reason and allow re-submission
• If VERIFIED: show a "KYC Verified" badge with verification date