fix: resolve broken documentation links causing Doc Build CI failure

[Copilot]

The Doc Build - Deploy CI job was failing due to 7 invalid links detected by starlight-links-validator across two files.

Changes

docs/astro.config.mjs

• Removed stale redirect '/reference/tokens/' → '/gh-aw/reference/auth/' that was set up when the tokens content was previously merged into auth. A new tokens.md page was later added at that same path, but the redirect was never removed — causing the link validator to reject auth.mdx's reference to /gh-aw/reference/tokens/ as an invalid link (the redirect page, not the content page, was being resolved).

docs/src/content/docs/reference/tokens.md

• Fixed 6 broken anchor hashes pointing to non-existent section IDs:

Was	Now	Target
#github-copilot-default	#available-coding-agents	engines.md
#claude-by-anthropic	#available-coding-agents	engines.md
#codex-by-openai	#available-coding-agents	engines.md
#gemini-by-google	#available-coding-agents	engines.md
#features	#feature-flags-features	frontmatter.md
#remote-vs-local-mode	#github-tools-remote-mode	github-tools.md

The engine entries are listed in a table under ## Available Coding Agents with no per-engine headings, so all four engine links correctly point to that section.

Original prompt

Fix the failing GitHub Actions workflow build
Analyze the workflow logs, identify the root cause of the failure, and implement a fix.
Job ID: 68653511321
Job URL: https://github.com/github/gh-aw/actions/runs/23577663811/job/68653511321

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[Copilot]

Pull request overview

Fixes Doc Build CI failures caused by invalid local documentation links by removing a redirect that shadowed an existing page and updating broken anchor hashes to point at valid section IDs.

Changes:

• Removed a stale /reference/tokens/ redirect that conflicted with the actual Token Reference page route.
• Updated broken section-anchor links in tokens.md to match current headings in engines.md, frontmatter.md, and github-tools.md.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
docs/astro.config.mjs	Removes a redirect that prevented /reference/tokens/ from resolving to the actual page.
docs/src/content/docs/reference/tokens.md	Fixes internal anchor hashes to point to existing sections, resolving link-validator failures.

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