feat: add Synology NAS, Home Assistant monitoring, multi-channel notifications

New tabs:
- Synology NAS: CPU, RAM, temp, volumes, VMs, Docker containers
- Home Assistant: sensors, automations, persons, climate, battery, doors

New features:
- Personalized PC agent download with custom name
- Notification settings: per-category Telegram/Email/WhatsApp toggles
- Email via SMTP, WhatsApp via CallMeBot API
- Test notification buttons for each channel
- Unified notifier replaces direct Telegram calls in alerter

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

server/api/notifications.py

@@ -0,0 +1,111 @@
+"""Notification settings and test endpoints."""
+
+from fastapi import APIRouter, Request, Depends
+
+from server.auth import require_auth
+from server.config import load_settings, save_settings
+
+router = APIRouter(prefix="/api/notifications", tags=["notifications"])
+
+
+@router.get("/settings")
+async def get_notification_settings(request: Request, user: str = Depends(require_auth)):
+    """Get notification preferences per category."""
+    settings = load_settings()
+    return {
+        "notifications": settings.get("notifications", {
+            "servers": {"telegram": True, "email": False, "whatsapp": False},
+            "pc": {"telegram": True, "email": False, "whatsapp": False},
+            "synology": {"telegram": True, "email": False, "whatsapp": False},
+            "ha": {"telegram": True, "email": False, "whatsapp": False},
+        }),
+        "email": {
+            "smtp_host": settings.get("smtp_host", ""),
+            "smtp_port": settings.get("smtp_port", 587),
+            "smtp_user": settings.get("smtp_user", ""),
+            "email_to": settings.get("email_to", ""),
+            "configured": bool(settings.get("smtp_host") and settings.get("smtp_user")),
+        },
+        "whatsapp": {
+            "phone": settings.get("whatsapp_phone", ""),
+            "configured": bool(settings.get("whatsapp_phone") and settings.get("whatsapp_apikey")),
+        },
+        "telegram": {
+            "configured": bool(settings.get("telegram_bot_token") and settings.get("telegram_chat_id")),
+        },
+    }
+
+
+@router.put("/settings")
+async def save_notification_settings(request: Request, user: str = Depends(require_auth)):
+    """Save notification preferences."""
+    body = await request.json()
+    settings = load_settings()
+
+    # Notification toggles per category
+    if "notifications" in body:
+        settings["notifications"] = body["notifications"]
+
+    # Email settings
+    if "smtp_host" in body:
+        settings["smtp_host"] = body["smtp_host"]
+    if "smtp_port" in body:
+        settings["smtp_port"] = int(body["smtp_port"])
+    if "smtp_user" in body:
+        settings["smtp_user"] = body["smtp_user"]
+    if "smtp_password" in body:
+        settings["smtp_password"] = body["smtp_password"]
+    if "email_to" in body:
+        settings["email_to"] = body["email_to"]
+
+    # WhatsApp settings
+    if "whatsapp_phone" in body:
+        settings["whatsapp_phone"] = body["whatsapp_phone"]
+    if "whatsapp_apikey" in body:
+        settings["whatsapp_apikey"] = body["whatsapp_apikey"]
+
+    save_settings(settings)
+    return {"status": "ok"}
+
+
+@router.post("/test/{channel}")
+async def test_notification(channel: str, request: Request, user: str = Depends(require_auth)):
+    """Send test notification via specified channel."""
+    from server.services.notifier import send_telegram, send_email, send_whatsapp
+
+    message = "🧪 Тест уведомления VPS Monitoring"
+    ok = False
+
+    if channel == "telegram":
+        ok = await send_telegram(message)
+    elif channel == "email":
+        ok = await send_email("Тест", message)
+    elif channel == "whatsapp":
+        ok = await send_whatsapp(message)
+    else:
+        return {"status": "error", "detail": f"unknown channel: {channel}"}
+
+    return {"status": "ok" if ok else "error", "channel": channel}
+
+
+@router.post("/generate-pc-agent")
+async def generate_pc_agent(request: Request, user: str = Depends(require_auth)):
+    """Generate personalized PC agent install command."""
+    body = await request.json()
+    agent_name = body.get("agent_name", "MyPC").strip()
+    server_url = body.get("server_url", "").strip()
+
+    if not server_url:
+        # Auto-detect
+        host = request.headers.get("host", "localhost:7272")
+        proto = "http"
+        server_url = f"{proto}://{host}"
+
+    cmd = (
+        f'powershell -ExecutionPolicy Bypass -Command '
+        f'"Invoke-WebRequest -Uri \'{server_url}/static/downloads/install_agent.ps1\' '
+        f'-OutFile install_agent.ps1; .\\install_agent.ps1 '
+        f'-ServerUrl \'{server_url}\' -AgentName \'{agent_name}\'"'
+    )
+
+    return {"status": "ok", "command": cmd, "agent_name": agent_name}