AI Prompt performance improvement for Standard users

Split AI food analysis prompt into Standard and Advanced mode to increase performance when in Standard Mode.
  - Standard Mode: ~2,500 words (basic analysis only)
  - Advanced Mode: ~6,000+ words (includes FPU calculations, deeper food absorption details, exercise guidance, etc.)
  - Token Reduction: ~60% fewer tokens for Standard mode users

  What this means for users:
  - Standard mode users get faster AI analysis with streamlined prompts
  - Advanced mode users get comprehensive analysis when they need FPU calculations
  - The system automatically chooses the right prompt based on the Advanced Dosing setting

Author: taylorpatterson-T1D