feat(mcp): add quarterly pyramid distribution lookup

backend/app/research_access/contracts.py

@@ -20,6 +20,12 @@ class Empty(Contract):
     pass
 
 
+class PyramidQuery(Contract):
+    current_date: date = Field(description="用于确定季度的日期，格式 YYYY-MM-DD；自动查询该季度完整起止范围")
+    region: str = Field(min_length=3, max_length=10, pattern=r"^[A-Z]+$")
+    delay: int = Field(ge=0, le=1, strict=True)
+
+
 class Authentication(Contract):
     action: Literal["connect", "verify"] = "connect"