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;

supabase/migrations/20260118090000_fix_get_detailed_availability_timezone.sql

@@ -0,0 +1,128 @@
+-- ============================================
+-- FIX: Mejorar get_detailed_availability para corregir problema de timezone
+-- Date: 20260118
+-- Description: Fix timezone conversion in availability function
+-- ============================================
+
+DROP FUNCTION IF EXISTS get_detailed_availability(p_location_id UUID, p_service_id UUID, p_date DATE, p_time_slot_duration_minutes INTEGER) CASCADE;
+
+CREATE OR REPLACE FUNCTION get_detailed_availability(
+    p_location_id UUID,
+    p_service_id UUID,
+    p_date DATE,
+    p_time_slot_duration_minutes INTEGER DEFAULT 60
+)
+RETURNS JSONB AS $$
+DECLARE
+    v_service_duration INTEGER;
+    v_location_timezone TEXT;
+    v_business_hours JSONB;
+    v_day_of_week TEXT;
+    v_day_hours JSONB;
+    v_open_time_text TEXT;
+    v_close_time_text TEXT;
+    v_start_time TIME;
+    v_end_time TIME;
+    v_time_slots JSONB := '[]'::JSONB;
+    v_slot_start TIMESTAMPTZ;
+    v_slot_end TIMESTAMPTZ;
+    v_available_staff_count INTEGER;
+    v_day_names TEXT[] := ARRAY['sunday', 'monday', 'tuesday', 'wednesday', 'thursday', 'friday', 'saturday'];
+BEGIN
+    -- Obtener duración del servicio
+    SELECT duration_minutes INTO v_service_duration
+    FROM services
+    WHERE id = p_service_id;
+
+    IF v_service_duration IS NULL THEN
+        RETURN '[]'::JSONB;
+    END IF;
+
+    -- Obtener zona horaria y horarios de la ubicación
+    SELECT
+        timezone,
+        COALESCE(business_hours, '{}'::jsonb)
+    INTO
+        v_location_timezone,
+        v_business_hours
+    FROM locations
+    WHERE id = p_location_id;
+
+    IF v_location_timezone IS NULL THEN
+        RETURN '[]'::JSONB;
+    END IF;
+
+    -- Obtener día de la semana (0 = Domingo, 1 = Lunes, etc.)
+    v_day_of_week := v_day_names[EXTRACT(DOW FROM p_date) + 1];
+
+    -- Obtener horarios para este día desde JSONB
+    v_day_hours := v_business_hours -> v_day_of_week;
+
+    -- Verificar si el lugar está cerrado este día
+    IF v_day_hours IS NULL OR v_day_hours->>'is_closed' = 'true' THEN
+        RETURN '[]'::JSONB;
+    END IF;
+
+    -- Extraer horas de apertura y cierre como TEXT primero
+    v_open_time_text := v_day_hours->>'open';
+    v_close_time_text := v_day_hours->>'close';
+
+    -- Convertir a TIME, usar defaults si están NULL
+    v_start_time := COALESCE(v_open_time_text::TIME, '10:00'::TIME);
+    v_end_time := COALESCE(v_close_time_text::TIME, '19:00'::TIME);
+
+    -- Generar slots de tiempo para el día
+    -- Construir timestamp en la timezone correcta
+    v_slot_start := make_timestamp(
+        EXTRACT(YEAR FROM p_date)::INTEGER,
+        EXTRACT(MONTH FROM p_date)::INTEGER,
+        EXTRACT(DAY FROM p_date)::INTEGER,
+        EXTRACT(HOUR FROM v_start_time)::INTEGER,
+        EXTRACT(MINUTE FROM v_start_time)::INTEGER,
+        0
+    )::TIMESTAMPTZ AT TIME ZONE v_location_timezone;
+
+    v_slot_end := make_timestamp(
+        EXTRACT(YEAR FROM p_date)::INTEGER,
+        EXTRACT(MONTH FROM p_date)::INTEGER,
+        EXTRACT(DAY FROM p_date)::INTEGER,
+        EXTRACT(HOUR FROM v_end_time)::INTEGER,
+        EXTRACT(MINUTE FROM v_end_time)::INTEGER,
+        0
+    )::TIMESTAMPTZ AT TIME ZONE v_location_timezone;
+
+    -- Iterar por cada slot
+    WHILE v_slot_start < v_slot_end LOOP
+        -- Verificar staff disponible para este slot
+        SELECT COUNT(*) INTO v_available_staff_count
+        FROM (
+            SELECT 1
+            FROM staff s
+            WHERE s.location_id = p_location_id
+            AND s.is_active = true
+            AND COALESCE(s.is_available_for_booking, true) = true
+            AND s.role IN ('artist', 'staff', 'manager')
+            AND check_staff_availability(s.id, v_slot_start, v_slot_start + (v_service_duration || ' minutes')::INTERVAL)
+        ) AS available_staff;
+
+        -- Agregar slot al resultado
+        IF v_available_staff_count > 0 THEN
+            v_time_slots := v_time_slots || jsonb_build_object(
+                'start_time', v_slot_start::TEXT,
+                'end_time', (v_slot_start + (p_time_slot_duration_minutes || ' minutes')::INTERVAL)::TEXT,
+                'available', true,
+                'available_staff_count', v_available_staff_count
+            );
+        END IF;
+
+        -- Avanzar al siguiente slot
+        v_slot_start := v_slot_start + (p_time_slot_duration_minutes || ' minutes')::INTERVAL;
+    END LOOP;
+
+    RETURN v_time_slots;
+END;
+$$ LANGUAGE plpgsql SECURITY DEFINER;
+
+GRANT EXECUTE ON FUNCTION get_detailed_availability TO authenticated, service_role;
+
+COMMENT ON FUNCTION get_detailed_availability IS 'Returns available time slots for booking with correct timezone handling';