Phase 1 | Priority: P0 | Status: Not Started | Covers: FR-001, FR-002

Context

Generates unique 8-char alphanumeric referral codes and returns the shareable link. Called when user visits the Invite Friends page.

Objective

Build POST /api/referrals/generate endpoint that creates or returns existing referral code for the authenticated user.

Acceptance Criteria

• Returns { code, link } where link = app.example.com/join/[CODE]
• Idempotent: calling twice returns same code
• Code is 8-char alphanumeric, case-insensitive
• Rate limited: max 10 generation requests per user per day
• Fires referral_link_generated analytics event
• Auth required (401 if unauthenticated)

Dependencies

Depends on: referral_codes table migration. Blocks: frontend Invite Friends page.