Resolve a generic EQ control onto the EQ row that owns it. The master engage is the /eq
row; a band is /eq/bands/{bandId} (positional, as the generic ids are); a pass filter is
/eq/filters/{filter}. The generic slope is an enum string ('12' | '24') and the filter
row stores the number, so it converts here rather than in every caller.
Resolve a generic EQ control onto the EQ row that owns it. The master engage is the
/eqrow; a band is/eq/bands/{bandId}(positional, as the generic ids are); a pass filter is/eq/filters/{filter}. The generic slope is an enum string ('12' | '24') and the filter row stores the number, so it converts here rather than in every caller.