Add bottle size, bourbon list modal, and stat improvements

- Add bottle_size field to User model and UserResponse/UserUpdate schemas
- Settings modal includes bottle size input (shots capacity)
- Community bottles and My Bottle page show fill bar based on bottle size
- Community bottle cards are clickable — opens searchable bourbon list modal
- Add total_shots_added stat to replace duplicate net volume on dashboard
- Reorder dashboard stats: Bourbons Added, Total Poured In, Shots Remaining, Est. Proof
- Theme-matched custom scrollbar (amber on dark)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/routers/public.py

@@ -31,11 +31,15 @@ async def public_stats(db: AsyncSession = Depends(get_db)):
         proof_shot_total = sum(e.amount_shots for e in adds if e.proof is not None)
         estimated_proof = round(weighted_proof_sum / proof_shot_total, 1) if proof_shot_total > 0 else None
 
+        bourbons = sorted({e.bourbon_name for e in adds if e.bourbon_name}, key=str.casefold)
+
         stats.append(PublicUserStats(
             display_name=user.display_name or user.email.split("@")[0],
             total_add_entries=len(adds),
             current_total_shots=round(current_total, 2),
             estimated_proof=estimated_proof,
+            bottle_size=user.bottle_size,
+            bourbons=bourbons,
         ))
 
     return stats