The orderByField/orderBy query params were passed straight into Eloquent's
orderBy() in every model's scopeWhereOrder (and Invoice::scopeApplyFilters),
allowing arbitrary SQL in the ORDER BY clause (boolean-based blind injection).
Adds App\Support\SafeOrderBy::apply() which only accepts a plain, optionally
table-qualified column identifier as the sort target (rejecting expressions,
sub-selects, etc.) and clamps the direction to asc/desc. Routed all 10 model
sort sinks through it. Table-qualified columns stay valid, so joined/aliased
sorts (e.g. estimates by customers.name) are unaffected.
Adds unit tests covering injection rejection, plain + aliased columns, and
direction clamping.
