fix(theme): correct highlight color to match design specifications

[hartou]

fix(layout-msagl): update nested option label for clarity

fix(presets): rename nested graph title to Microservice Architecture

refactor(list): change itemPosition return type for better type safety

fix(arrow): correct SVG import filename to match casing

fix(plus): correct SVG import filename to match casing

Description

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Motivation and Context

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[kumilingus]

Hi @hartou , thanks for the PR! Could you share the motivation behind these changes? At first glance, it looks like it may have been generated automatically, so any context would be helpful.