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/whatsapp/client.py

@@ -0,0 +1,21 @@
+import httpx
+
+GRAPH_API_VERSION = "v20.0"
+GRAPH_API_BASE = f"https://graph.facebook.com/{GRAPH_API_VERSION}"
+
+
+async def send_text_message(phone_number_id: str, access_token: str, to: str, text: str) -> None:
+    url = f"{GRAPH_API_BASE}/{phone_number_id}/messages"
+    payload = {
+        "messaging_product": "whatsapp",
+        "to": to,
+        "type": "text",
+        "text": {"body": text},
+    }
+    async with httpx.AsyncClient() as client:
+        response = await client.post(
+            url,
+            json=payload,
+            headers={"Authorization": f"Bearer {access_token}"},
+        )
+    response.raise_for_status()