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/services/notifications.py

@@ -0,0 +1,147 @@
+"""
+Notification service for alerts and summaries.
+"""
+
+import httpx
+from typing import Optional
+
+from app.core.config import settings
+
+
+async def telegram_notify(
+    message: str,
+    parse_mode: str = "Markdown",
+    disable_notification: bool = False
+) -> bool:
+    """
+    Send a notification via Telegram.
+
+    Args:
+        message: Message text (supports Markdown)
+        parse_mode: "Markdown" or "HTML"
+        disable_notification: If True, send silently
+
+    Returns:
+        True if sent successfully
+    """
+    if not settings.TELEGRAM_BOT_TOKEN or not settings.TELEGRAM_CHAT_ID:
+        return False
+
+    url = f"https://api.telegram.org/bot{settings.TELEGRAM_BOT_TOKEN}/sendMessage"
+
+    payload = {
+        "chat_id": settings.TELEGRAM_CHAT_ID,
+        "text": message,
+        "parse_mode": parse_mode,
+        "disable_notification": disable_notification
+    }
+
+    try:
+        async with httpx.AsyncClient() as client:
+            response = await client.post(url, json=payload)
+            return response.status_code == 200
+    except Exception:
+        return False
+
+
+async def telegram_notify_error(
+    error: str,
+    context: Optional[str] = None
+) -> bool:
+    """Send error notification."""
+    message = f"🚨 *Error*\n\n{error}"
+    if context:
+        message += f"\n\n📍 Contexto: {context}"
+
+    return await telegram_notify(message)
+
+
+async def telegram_notify_success(
+    title: str,
+    details: Optional[str] = None
+) -> bool:
+    """Send success notification."""
+    message = f"✅ *{title}*"
+    if details:
+        message += f"\n\n{details}"
+
+    return await telegram_notify(message)
+
+
+class NotificationService:
+    """Service for managing notifications."""
+
+    def __init__(self):
+        self.telegram_enabled = bool(
+            settings.TELEGRAM_BOT_TOKEN and settings.TELEGRAM_CHAT_ID
+        )
+
+    async def notify_publish(
+        self,
+        platform: str,
+        content: str,
+        url: Optional[str] = None,
+        success: bool = True
+    ):
+        """Notify about a publication."""
+        if not self.telegram_enabled:
+            return
+
+        emoji = "✅" if success else "❌"
+        status = "Publicado" if success else "Error al publicar"
+
+        message = f"{emoji} *{status} en {platform}*\n\n"
+        message += f"📝 {content[:150]}..."
+
+        if url:
+            message += f"\n\n🔗 {url}"
+
+        await telegram_notify(message)
+
+    async def notify_interaction(
+        self,
+        platform: str,
+        author: str,
+        content: str,
+        interaction_type: str = "comentario"
+    ):
+        """Notify about a new interaction."""
+        if not self.telegram_enabled:
+            return
+
+        message = f"💬 *Nueva interacción en {platform}*\n\n"
+        message += f"👤 @{author}\n"
+        message += f"📝 {content[:200]}"
+
+        await telegram_notify(message)
+
+    async def notify_daily_summary(
+        self,
+        published: int,
+        failed: int,
+        scheduled: int,
+        interactions: int
+    ):
+        """Send daily summary."""
+        if not self.telegram_enabled:
+            return
+
+        message = "📊 *Resumen del día*\n\n"
+        message += f"✅ Publicados: {published}\n"
+        if failed > 0:
+            message += f"❌ Fallidos: {failed}\n"
+        message += f"📅 Programados: {scheduled}\n"
+        message += f"💬 Interacciones: {interactions}"
+
+        await telegram_notify(message)
+
+    async def notify_error(self, error: str, context: str = None):
+        """Send error notification."""
+        if not self.telegram_enabled:
+            return
+
+        await telegram_notify_error(error, context)
+
+
+# Global instance
+notification_service = NotificationService()