Extracts the prompt templates for daily schedule and monthly plan generation from `llm_generator.py` into a new `prompts.py` module. This change centralizes prompt management and improves code readability and maintainability by separating prompt logic from the generation workflow.
The `ScheduleLLMGenerator` and `MonthlyPlanLLMGenerator` classes now use the `global_prompt_manager` to format and retrieve the necessary prompts, simplifying the generator code.
