I need a cycling workout in JSON format for the Zwift Hub Controller app.

Please create a workout with the following requirements:
- Workout goal: [e.g., "Sweet spot endurance", "VO2 max intervals", "FTP test"]
- Duration: [e.g., "60 minutes", "90 minutes"]
- Difficulty level: [e.g., "beginner", "intermediate", "advanced"]
- Special requirements: [any specific needs]

The JSON format should follow this structure:

{
  "name": "Workout Name",
  "description": "Brief description of the workout",
  "ftp": 200,
  "intervals": [
    {
      "name": "Interval Name",
      "type": "warmup|endurance|tempo|threshold|vo2max|cooldown",
      "duration": 300,
      "powerType": "relative|absolute|ramp",
      "percentage": 60  // for relative power
      // OR
      "power": 150  // for absolute power in watts
      // OR for ramps:
      "percentageLow": 50,
      "percentageHigh": 80
    }
  ],
  "created": "2025-01-15T12:00:00.000Z",
  "version": "1.0"
}

Power type rules:
- relative (% of FTP): Use for most intervals. Percentage between 10-200.
- absolute (fixed watts): Use for specific power targets or ramp tests.
- ramp (gradual increase): Use percentageLow and percentageHigh for smooth power transitions.

Interval types and typical power zones:
- warmup: 40-60% FTP
- endurance: 55-75% FTP
- tempo: 76-87% FTP
- threshold: 88-105% FTP
- vo2max: 106-120% FTP
- cooldown: 40-50% FTP

Please ensure:
1. Workout starts with a proper warmup (10-15 minutes)
2. Include recovery periods between hard efforts
3. End with an adequate cooldown (10 minutes)
4. Total duration matches my request
5. Progression is logical and safe

Return only the valid JSON, no additional explanation.