Dead 'dups' mode template in duplicate-aliases.xsl emitting outdated 'error' element

Problem

duplicate-aliases.xsl contains a dead template (mode="dups") that is never invoked, and it emits an outdated <error> element instead of a <defect>.

Details

src/main/resources/org/eolang/lints/aliases/duplicate-aliases.xsl:37-54:

<xsl:template match="meta" mode="dups">
  <xsl:for-each select="/object/metas/meta[head='alias']">
    ...
    <error>
      ...
    </error>
  </xsl:for-each>
</xsl:template>

Two issues:

1. Dead code. The mode="dups" template is declared but never invoked — there is no <xsl:apply-templates ... mode="dups"> anywhere in the file (confirmed by grep: the only occurrence of dups is the template declaration). So this template never runs and produces nothing.

2. Outdated element name. Even if it were invoked, it emits <error> (the old defect format used by eo-parser), while the project's defect contract is <defect> (see LtByXsl / the existing packs for this lint, which assert against /defects/defect). The real, active logic of the lint lives in the default template above it, which correctly produces <defect>.

Impact

• Dead code adds confusion: a reader may think the mode="dups" path is part of the lint's behavior, but it is unreachable.
• If someone "fixes" the invocation later, the lint would start emitting <error> elements that break the /defects/defect contract and would not be picked up by LtByXsl.
• Minor, but it is the kind of leftover that the errors/empty-object or comment-without-dot lints got cleaned up of before.

Expected behaviour

Remove the dead mode="dups" template (and any <error> usage) so the file contains only the working <defect>-based logic. A simple code cleanup with no behavior change.