feat: initial commit — HermesMessages SaaS platform

Backend (FastAPI + Python 3.12):
- Multi-tenant auth with JWT: login, register, refresh, Meta OAuth
- Business & BusinessConfig management
- WhatsApp webhook with HMAC signature verification
- Bot engine powered by Claude AI
- Calendar availability with Redis caching
- Reservations CRUD with status management
- Dashboard analytics (stats, agenda, peak hours)
- Billing & plan management
- Admin panel with platform-wide stats
- Async bcrypt via asyncio.to_thread
- IntegrityError handling for concurrent registration race conditions

Frontend (React 18 + Vite + Tailwind CSS):
- Multi-step guided registration form with helper text on every field
- Login page with show/hide password toggle
- Protected routes with AuthContext
- Dashboard with stats cards, bar chart, and daily agenda
- Reservations list with search, filters, and inline status actions
- Calendar with weekly view, slot availability, and date blocking
- Config page: business info, schedules, bot personality
- Billing page with plan comparison and usage bar

Design system:
- Bricolage Grotesque + DM Sans typography
- Emerald primary palette with semantic color tokens
- scale(0.97) button press feedback, ease-out animations
- Skeleton loaders, stagger animations, prefers-reduced-motion support
- Accessible: aria-labels, visible focus rings, 4.5:1 contrast

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

backend/app/modules/notifications/service.py

@@ -0,0 +1,47 @@
+import logging
+
+from app.modules.whatsapp.client import send_text_message
+
+logger = logging.getLogger(__name__)
+
+
+async def send_reservation_confirmation(
+    phone_number_id: str,
+    access_token: str,
+    client_phone: str,
+    client_name: str,
+    reservation_date: str,
+    time_start: str,
+    business_name: str,
+) -> None:
+    message = (
+        f"✅ Reserva confirmada, {client_name}!\n\n"
+        f"📅 Fecha: {reservation_date}\n"
+        f"🕐 Hora: {time_start}\n"
+        f"📍 {business_name}\n\n"
+        "Te esperamos. Si necesitas cancelar, contáctanos."
+    )
+    try:
+        await send_text_message(phone_number_id, access_token, client_phone, message)
+    except Exception as exc:
+        logger.warning("No se pudo enviar confirmación a %s: %s", client_phone, exc)
+
+
+async def send_reservation_reminder(
+    phone_number_id: str,
+    access_token: str,
+    client_phone: str,
+    client_name: str,
+    reservation_date: str,
+    time_start: str,
+    business_name: str,
+) -> None:
+    message = (
+        f"👋 Hola {client_name}, te recordamos tu reserva en {business_name}.\n\n"
+        f"📅 {reservation_date} a las {time_start}\n\n"
+        "¡Te esperamos!"
+    )
+    try:
+        await send_text_message(phone_number_id, access_token, client_phone, message)
+    except Exception as exc:
+        logger.warning("No se pudo enviar recordatorio a %s: %s", client_phone, exc)