v3 port. orderByField/orderBy were passed straight into Eloquent's orderBy()
in every model's scopeWhereOrder (and Invoice::scopeApplyFilters), allowing
arbitrary SQL in the ORDER BY clause.
Adds App\Support\SafeOrderBy::apply() (plain/table-qualified column identifier
only, asc/desc clamp) and routes all 10 model sort sinks through it. Aliased
sorts (e.g. estimates by customers.name) stay valid.
Adds unit tests for injection rejection, plain + aliased columns, direction clamp.
ca6dd57bf9