The Y1 Monthly Sales Target fields don't match the Y1_M<n>_<metric> regex
the monthly matrix collector uses to discover rows:
M1 -> Y1_Monthly_Sales_Targets (no _M1 suffix; trailing 's')
M2 -> Y1_Monthly_Sales_Targets_M2 (plural with _M2)
M3 -> Y1_Monthly_Sales_Target_M2 (Civi name says _M2 but the value
represents M3; pre-existing
schema error)
M4..M12 -> Y1_Monthly_Sales_Target_M<n>
Hardcode a period->civi-field-name map (Y1_MONTHLY_SALES_TARGET_FIELDS)
so the monthly matrix can pick these up alongside the regex-matched
Y1_M<n>_Actual_Sales / Y1_M<n>_Transactions rows. The M3->_M2
irregularity is called out inline so a future reader doesn't "fix" it
into a regression.