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/auth/service.py

@@ -0,0 +1,153 @@
+import asyncio
+import httpx
+from datetime import time as dtime
+
+from fastapi import HTTPException, status
+from sqlalchemy import select
+from sqlalchemy.exc import IntegrityError
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.config import settings
+from app.core.security import create_access_token, hash_password, verify_password
+from app.modules.auth.models import User
+from app.modules.business.models import Business, BusinessConfig
+
+
+def _token_for_user(user: User) -> str:
+    return create_access_token({"sub": str(user.id), "business_id": user.business_id})
+
+
+async def register_business(
+    db: AsyncSession,
+    business_name: str,
+    business_type: str,
+    timezone: str,
+    email: str,
+    password: str,
+) -> tuple[str, int, int]:
+    existing = await get_user_by_email(db, email)
+    if existing:
+        raise HTTPException(
+            status_code=status.HTTP_409_CONFLICT,
+            detail="El correo ya está registrado",
+        )
+
+    business = Business(
+        name=business_name,
+        type=business_type,
+        timezone=timezone,
+        status="trial",
+        plan="free",
+    )
+    db.add(business)
+    await db.flush()
+
+    db.add(
+        BusinessConfig(
+            business_id=business.id,
+            open_days=[0, 1, 2, 3, 4],
+            open_time=dtime(9, 0),
+            close_time=dtime(18, 0),
+            slot_duration=60,
+            max_per_slot=1,
+            blocked_dates=[],
+            assistant_name="Hermes",
+            tone="formal",
+        )
+    )
+
+    hashed = await asyncio.to_thread(hash_password, password)
+    user = User(
+        business_id=business.id,
+        email=email,
+        hashed_password=hashed,
+        role="owner",
+    )
+    db.add(user)
+    await db.flush()
+
+    try:
+        await db.commit()
+    except IntegrityError:
+        await db.rollback()
+        raise HTTPException(
+            status_code=status.HTTP_409_CONFLICT,
+            detail="El correo ya está registrado",
+        )
+
+    return _token_for_user(user), business.id, user.id
+
+
+async def get_user_by_id(db: AsyncSession, user_id: int) -> User | None:
+    result = await db.execute(select(User).where(User.id == user_id))
+    return result.scalar_one_or_none()
+
+
+async def get_user_by_email(db: AsyncSession, email: str) -> User | None:
+    result = await db.execute(select(User).where(User.email == email))
+    return result.scalar_one_or_none()
+
+
+async def authenticate_user(db: AsyncSession, email: str, password: str) -> str:
+    user = await get_user_by_email(db, email)
+    if not user or not user.hashed_password:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Credenciales incorrectas",
+        )
+    if not await asyncio.to_thread(verify_password, password, user.hashed_password):
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Credenciales incorrectas",
+        )
+    return _token_for_user(user)
+
+
+async def exchange_meta_code(code: str, redirect_uri: str) -> dict:
+    """Intercambia el código de autorización de Meta por un access token."""
+    async with httpx.AsyncClient() as client:
+        response = await client.get(
+            "https://graph.facebook.com/v20.0/oauth/access_token",
+            params={
+                "client_id": settings.META_APP_ID,
+                "client_secret": settings.META_APP_SECRET,
+                "code": code,
+                "redirect_uri": redirect_uri,
+            },
+        )
+    if response.status_code != 200:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="Error al intercambiar código con Meta",
+        )
+    return response.json()
+
+
+async def get_meta_user_info(access_token: str) -> dict:
+    async with httpx.AsyncClient() as client:
+        response = await client.get(
+            "https://graph.facebook.com/me",
+            params={"fields": "id,email", "access_token": access_token},
+        )
+    if response.status_code != 200:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="Error al obtener información del usuario de Meta",
+        )
+    return response.json()
+
+
+async def meta_oauth_login(db: AsyncSession, code: str, redirect_uri: str) -> str:
+    token_data = await exchange_meta_code(code, redirect_uri)
+    meta_info = await get_meta_user_info(token_data["access_token"])
+
+    result = await db.execute(select(User).where(User.meta_user_id == meta_info["id"]))
+    user = result.scalar_one_or_none()
+
+    if not user:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Usuario no encontrado. Completa el registro primero.",
+        )
+
+    return _token_for_user(user)