feat(phase-4): Complete scheduling and automation system

- Add Celery worker with 5 scheduled tasks (Beat)
- Create ContentScheduler for optimal posting times
- Add calendar endpoints for scheduled posts management
- Implement Telegram notification service
- Add notification API with setup guide

Celery Beat Schedule:
- check_scheduled_posts: Every minute
- generate_daily_content: Daily at 6 AM
- sync_interactions: Every 15 minutes
- send_daily_summary: Daily at 9 PM
- cleanup_old_data: Weekly on Sundays

New endpoints:
- GET /api/calendar/posts/scheduled - List scheduled posts
- GET /api/calendar/posts/view - Calendar view
- GET /api/calendar/posts/slots - Available time slots
- POST /api/calendar/posts/{id}/schedule - Schedule post
- POST /api/calendar/posts/{id}/publish-now - Publish immediately
- GET /api/notifications/status - Check notification config
- POST /api/notifications/test - Send test notification
- GET /api/notifications/setup-guide - Configuration guide

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/api/routes/notifications.py

@@ -0,0 +1,143 @@
+"""
+API Routes for notification management.
+"""
+
+from fastapi import APIRouter, HTTPException
+from pydantic import BaseModel
+from typing import Optional
+
+from app.core.config import settings
+from app.services.notifications import telegram_notify, notification_service
+
+
+router = APIRouter()
+
+
+class TestNotificationRequest(BaseModel):
+    """Request for testing notifications."""
+    message: Optional[str] = "Test desde Social Media Automation"
+
+
+class NotificationSettingsResponse(BaseModel):
+    """Response with notification settings."""
+    telegram_configured: bool
+    bot_token_set: bool
+    chat_id_set: bool
+
+
+@router.get("/status")
+async def get_notification_status():
+    """
+    Verificar estado de las notificaciones.
+
+    Muestra si Telegram está configurado correctamente.
+    """
+    return NotificationSettingsResponse(
+        telegram_configured=notification_service.telegram_enabled,
+        bot_token_set=bool(settings.TELEGRAM_BOT_TOKEN),
+        chat_id_set=bool(settings.TELEGRAM_CHAT_ID)
+    )
+
+
+@router.post("/test")
+async def test_notification(request: TestNotificationRequest):
+    """
+    Enviar notificación de prueba.
+
+    Útil para verificar que la configuración de Telegram funciona.
+    """
+    if not notification_service.telegram_enabled:
+        raise HTTPException(
+            status_code=503,
+            detail="Telegram no configurado. Agrega TELEGRAM_BOT_TOKEN y TELEGRAM_CHAT_ID en .env"
+        )
+
+    message = f"🧪 *Test de Notificación*\n\n{request.message}\n\n✅ Si ves esto, las notificaciones funcionan correctamente."
+
+    success = await telegram_notify(message)
+
+    if success:
+        return {"success": True, "message": "Notificación enviada"}
+    else:
+        raise HTTPException(
+            status_code=500,
+            detail="Error al enviar notificación. Verifica las credenciales."
+        )
+
+
+@router.post("/send")
+async def send_custom_notification(
+    message: str,
+    parse_mode: str = "Markdown"
+):
+    """
+    Enviar notificación personalizada.
+
+    - **message**: Texto del mensaje (soporta Markdown)
+    - **parse_mode**: "Markdown" o "HTML"
+    """
+    if not notification_service.telegram_enabled:
+        raise HTTPException(
+            status_code=503,
+            detail="Telegram no configurado"
+        )
+
+    success = await telegram_notify(message, parse_mode)
+
+    return {"success": success}
+
+
+@router.get("/setup-guide")
+async def get_setup_guide():
+    """
+    Obtener guía de configuración de Telegram.
+    """
+    return {
+        "title": "Configuración de Notificaciones Telegram",
+        "steps": [
+            {
+                "step": 1,
+                "title": "Crear Bot de Telegram",
+                "instructions": [
+                    "Abre Telegram y busca @BotFather",
+                    "Envía el comando /newbot",
+                    "Sigue las instrucciones para nombrar tu bot",
+                    "Guarda el token que te proporciona"
+                ]
+            },
+            {
+                "step": 2,
+                "title": "Obtener Chat ID",
+                "instructions": [
+                    "Inicia una conversación con tu nuevo bot",
+                    "Envía cualquier mensaje",
+                    "Visita: https://api.telegram.org/bot<TU_TOKEN>/getUpdates",
+                    "Busca el campo 'chat': {'id': XXXXXXX}",
+                    "Ese número es tu CHAT_ID"
+                ]
+            },
+            {
+                "step": 3,
+                "title": "Configurar Variables",
+                "instructions": [
+                    "Edita tu archivo .env",
+                    "Agrega: TELEGRAM_BOT_TOKEN=tu_token_aqui",
+                    "Agrega: TELEGRAM_CHAT_ID=tu_chat_id_aqui",
+                    "Reinicia la aplicación"
+                ]
+            },
+            {
+                "step": 4,
+                "title": "Verificar",
+                "instructions": [
+                    "Usa el endpoint POST /api/notifications/test",
+                    "Deberías recibir un mensaje en Telegram"
+                ]
+            }
+        ],
+        "current_status": {
+            "configured": notification_service.telegram_enabled,
+            "bot_token": "✓ Configurado" if settings.TELEGRAM_BOT_TOKEN else "✗ Falta",
+            "chat_id": "✓ Configurado" if settings.TELEGRAM_CHAT_ID else "✗ Falta"
+        }
+    }