`no-attribute-formation` XSL transformation is too slow on large XMIR files

I'm getting performance warnings when running lints against eo-runtime:

[WARNING] XSL transformation 'no-attribute-formation' took 114ms, whereas threshold is 100ms

What happens: The XPath predicate includes:

not(ancestor::o[eo:abstract(.) and @name and o[@base='∅']])

For every candidate <o> element, this walks the entire ancestor chain and for each ancestor checks all its children (o[@base='∅']). The cost is O(n × depth × degree). On large deeply nested XMIR this compounds quickly.

What should happen: The transformation completes within the 100ms threshold. Pre-computing which objects have void attributes (e.g., with xsl:key) and checking ancestor names via an index would avoid the repeated child scans.