Replace freeform interests with a richer interests and passions UI

[willdaly]

Summary

The whiteboard suggests interests through bubbles, passions, and lightweight tags such as zodiac signs. The current onboarding uses a simple comma-separated interests field.

Scope

• replace the current freeform interests input with a more structured selection experience
• support primary interests plus deeper passions or affinity tags
• keep the UI fast enough for demo and hackathon onboarding

Acceptance criteria

• users can select interests in a structured way instead of typing only comma-separated text
• the data model distinguishes between broad interests and more specific passions or tags
• selected interests are visible in downstream matching or profile views