Loops over audit_weak_types + audit_exception_handling from
the 6 audit_inputs, calls aggregate_cross_audit_findings per
audit, sums the buckets per profile.
Cross-audit aggregation is per-aggregate-flat (all findings go
into 1 bucket per audit). The 3-tier finding-to-aggregate
mapping (find_enclosing_function + type registry + file
heuristic) is the next gap - requires per-finding site
classification.