Restructure core style guide to remove redundancy with system prompt
Core style guide: https://gitlab.com/gitlab-com/localization/gitlab-duo-agent-translation-platform/-/blob/main/specifications/core/gitlab-translation-styleguide.md
The [**gitlab-translation-styleguide.md**](https://gitlab.com/gitlab-com/localization/gitlab-duo-agent-translation-platform/-/blob/main/specifications/core/gitlab-translation-styleguide.md?ref_type=heads) file mixes several different types of content that should ideally be separated, for example
* a) [style guidance](https://gitlab.com/gitlab-com/localization/gitlab-duo-agent-translation-platform/-/blob/main/specifications/core/gitlab-translation-styleguide.md?ref_type=heads&plain=1#L36) (which belongs to the guide on style conceptually),
* b) [workflow instructions](https://gitlab.com/gitlab-com/localization/gitlab-duo-agent-translation-platform/-/blob/main/specifications/core/gitlab-translation-styleguide.md?ref_type=heads&plain=1#L5) (which rather belong in the system prompt),
* c) [operational procedures about MR creation](https://gitlab.com/gitlab-com/localization/gitlab-duo-agent-translation-platform/-/blob/main/specifications/core/gitlab-translation-styleguide.md?ref_type=heads&plain=1#L5), or [directory structure](https://gitlab.com/gitlab-com/localization/gitlab-duo-agent-translation-platform/-/blob/main/specifications/core/gitlab-translation-styleguide.md?ref_type=heads&plain=1#L140) (which I am not sure where should belong, maybe system prompt).
**After this work / success criteria**
* Core style guide will contain only relevant style guidance (TBD what it is, maybe SEO limits, what to translate / never translate)
* System prompt will contain workflow instructions and operational procedures (MR creation, directory mapping, validation checklists)
* No duplicated content between the two files
issue