[information-architecture] Unify Text Auditor naming across docs navigation and workflow pages

The Text Auditor workflow is exposed under materially different user-facing names across the primary docs paths, which can make users wonder whether "Text Quality" and "Text Auditor" are separate workflows when selecting or installing add-ons.

Evidence:
- `mkdocs.yml:53` lists the navigation item as **Text Quality**.
- `docs/workflows/gh-agent-workflows/text-quality.md:1` titles the destination page **Text Quality**, but `docs/workflows/gh-agent-workflows/text-quality.md:5` and `:19` switch to **Text Auditor**.
- `docs/workflows/gh-agent-workflows.md:80` lists the workflow as **Text Auditor** while linking to `gh-agent-workflows/text-quality.md`.
- `gh-agent-workflows/README.md:27` and `gh-agent-workflows/text-auditor/README.md:1` also use **Text Auditor**.
- Installation examples use the `text-auditor` source path and output filename (`docs/workflows/gh-agent-workflows/text-quality.md:13-14`, `gh-agent-workflows/text-auditor/README.md:13-14`).

User impact:
A user browsing the docs nav sees "Text Quality", lands on a page that alternates between "Text Quality" and "Text Auditor", then installs from a `text-auditor` path. This weakens hierarchy/consistency in the workflow picker experience and can make workflow selection look like it contains aliases or separate options.

Suggested fix:
Pick one canonical display name, preferably **Text Auditor** to match the workflow name, source directory, example workflow, and overview table, then update the MkDocs nav and page title or add explicit alias copy if "Text Quality" is intentionally the category label.

Duplicate risk assessment:
Known prior IA issues provided in the assignment cover other discovery/category problems, but not this Text Auditor/Text Quality naming split. A targeted GitHub issue search did not find an open issue specifically about the naming inconsistency; related Text Auditor docs issues appear to concern action placement/progressive disclosure, so duplicate risk is low to medium.

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Compare the naming in mkdocs.yml, docs/workflows/gh-agent-workflows/text-quality.md, docs/workflows/gh-agent-workflows.md, gh-agent-workflows/README.md, and gh-agent-workflows/text-auditor/README.md. Start with the listed navigation and page-title lines, then verify the installation examples and workflow overview. Done means the chosen display name is consistent across navigation, pages, overview text, and installation context, or the alias relationship is explicit.

Written by the indexing model from the issue text.