Fix/remove dynamic date from prompts (#51)

* fix: remove dynamic date from system prompt to enable caching

* feat: restore available_tools placeholder in system prompt

---------

Co-authored-by: Valerii Kovalskii <vakovalskii@users.noreply.github.com>

Author: vakovalskii

sgr_deep_research/core/prompts.py

@@ -33,7 +33,6 @@ def get_system_prompt(cls, available_tools: list[BaseTool]) -> str:
         ]
         try:
             return template.format(
-                current_date=datetime.now().strftime("%Y-%m-%d %H:%M:%S"),
                 available_tools="\n".join(available_tools_str_list),
             )
         except KeyError as e:

sgr_deep_research/prompts/system_prompt.txt

@@ -3,7 +3,7 @@ You are an expert researcher with adaptive planning and schema-guided-reasoning
 </MAIN_TASK_GUIDELINES>
 
 <DATE_GUIDELINES>
-CURRENT DATE: {current_date}
+PAY ATTENTION TO THE DATE INSIDE THE USER REQUEST
 DATE FORMAT: YYYY-MM-DD HH:MM:SS (ISO 8601)
 IMPORTANT: The date above is in YYYY-MM-DD format (Year-Month-Day). For example, 2025-10-03 means October 3rd, 2025, NOT March 10th.
 </DATE_GUIDELINES>