fix: Correct calendar offset and fix business hours showing only 22:00-23:00

FIX 1 - Calendar Day Offset (already fixed in previous commit):
- Corrected DatePicker component to calculate proper day offset
- Added padding cells for correct weekday alignment
- January 1, 2026 now correctly shows as Thursday instead of Monday

FIX 2 - Business Hours Only Showing 22:00-23:00:
PROBLEM:
- Time slots API only returned 22:00 and 23:00 as available hours
- Incorrect business hours in database (likely 22:00-23:00 instead of 10:00-19:00)
- Poor timezone conversion in get_detailed_availability function

ROOT CAUSES:
1. Location business_hours stored incorrect hours (22:00-23:00)
2. get_detailed_availability had timezone concatenation issues
   - Used string concatenation for timestamp construction
   - Didn't properly handle timezone conversion
3. Fallback to defaults was using wrong values

SOLUTIONS:
1. Migration 20260118080000_fix_business_hours_default.sql:
   - Update default business hours to normal salon hours
   - Mon-Fri: 10:00-19:00
   - Saturday: 10:00-18:00
   - Sunday: Closed

2. Migration 20260118090000_fix_get_detailed_availability_timezone.sql:
   - Rewrite get_detailed_availability function
   - Use make_timestamp() instead of string concatenation
   - Proper timezone handling with AT TIME ZONE
   - Better NULL handling for business_hours
   - Fix is_available_for_booking COALESCE to default true

CHANGES:
- components/booking/date-picker.tsx: Added day offset calculation
- supabase/migrations/20260118080000.sql: Fix default business hours
- supabase/migrations/20260118090000.sql: Fix timezone in availability function

supabase/migrations/20260118080000_fix_business_hours_default.sql

@@ -0,0 +1,25 @@
+-- ============================================
+-- FIX: Corregir horarios de negocio por defecto
+-- Date: 20260118
+-- Description: Fix business hours that only show 22:00-23:00
+-- ============================================
+
+-- Verificar horarios actuales
+SELECT id, name, timezone, business_hours FROM locations;
+
+-- Actualizar horarios de negocio a horarios normales
+UPDATE locations
+SET business_hours = '{
+  "monday": {"open": "10:00", "close": "19:00", "is_closed": false},
+  "tuesday": {"open": "10:00", "close": "19:00", "is_closed": false},
+  "wednesday": {"open": "10:00", "close": "19:00", "is_closed": false},
+  "thursday": {"open": "10:00", "close": "19:00", "is_closed": false},
+  "friday": {"open": "10:00", "close": "19:00", "is_closed": false},
+  "saturday": {"open": "10:00", "close": "18:00", "is_closed": false},
+  "sunday": {"is_closed": true}
+}'::jsonb
+WHERE business_hours IS NULL 
+   OR business_hours = '{}'::jsonb;
+
+-- Verificar que los horarios se actualizaron correctamente
+SELECT id, name, timezone, business_hours FROM locations;