fix: redesign venue into 2-column showcase and remove speaker dinner perk

[esrakadah]

Summary of Changes

1. Date & Venue Section Redesign (Goodbye flat wireframe!):

   • Replaced the single flat, empty card with a balanced 2-column showcase layout:
     • Left Column (Visual Showcase & Facilities): Tech dark gradient card with Berlin Neukölln badge, event date pill, architectural illustration, and 4 campus facility highlights (Keynote Auditoriums, 100% Barrier-Free Access, Gigabit WiFi, Secure Bike Racks).
     • Right Column (Transit Hub & Actions): Clean typography, exact Sonnenallee address with interactive 1-Click Copy Address button, transit route cards for S-Bahn (S41/S42/S45/S46/S47), MetroBus (M41), and Car/Bike access via A100.
     • Unified Action Buttons: Polished Google Blue for Google Maps, sleek dark navy/yellow for BVG Route Planner, and clean border for Add to Calendar.

2. Speaker Perks Cleanup:

   • Removed 'Speaker Dinner & Mixer' as requested.
   • Refactored .perks-grid to a balanced 3-column grid for the remaining perks.

3. Negative Constraint Check:

   • Verified 0 mentions of Hackathon or Vibe Lounge across the entire codebase.