`line-is-absent` lint falsely reports objects with duplicate names in different scopes

Problem

The line-is-absent lint uses a global key by object name.

In src/main/resources/org/eolang/lints/refs/line-is-absent.xsl, the lookup is based on @name only, and it does not take lexical scope into account.

What happens

If an XMIR document contains two objects with the same name in different scopes, and one of them has no @line, a reference to the other one may still trigger line-is-absent.

That creates a false positive: the lint reports a missing @line on an unrelated object that is not the actual resolution target.

Why this is a bug

The rule is supposed to verify the referenced object, not any object in the document that happens to share the same name.

A global key by @name is not enough when the same name is reused in different lexical scopes.

What should happen

The lint should only report line-is-absent when the object actually resolved by the reference lacks @line.

Objects with the same name in unrelated scopes should not affect the result.