feat: restructure application form (10 steps), add sponsorship tiers, consolidate CTAs
- Restructure apply form: landing screen, pricing at step 1, theme picker,
belief update, review & pay step, localStorage autosave, warm success state
- Add 7 new DB columns (migration-004): selected_weeks, top_themes,
belief_update, volunteer_interest, coupon_code, food_preference, accessibility_needs
- Update confirmation emails: 1-week review timeline, warmer tone
- Add sponsorship tiers page (Friend/Symbiont/Spore/Mycelium)
- Consolidate all "Apply Now" → "Register Now", remove duplicate CTAs
- Add new fields to admin panel display
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>