docs: add LLM equivalents for Dashboard screenshots

[Devon-White]

Summary

• hide Dashboard and related instructional screenshots and their expiring image URLs from Markdown exports
• add page-specific text equivalents for navigation, settings, wizard state, and the two legacy SWML Dashboard screenshots
• share only the nine identical TTS assignment blocks
• add local/manual deployed-preview assertions for every affected route and key workflow; the checker is intentionally not wired into CI

Scope

This is PR 4 in the stacked implementation for #388 and depends on #612. The final audit also found and covered five screenshots stored outside the /assets/images/dashboard/ path: three WireStarter/SWSH captures and two legacy SWML Dashboard captures.

Validation

• yarn test:scripts
• yarn fern-md-check
• git diff --check
• yarn check-llm-exports after the Fern preview deploys
• source audit confirms every Dashboard image reference is inside llms-ignore
• the manual checker rejects presigned image URLs on every tested route

Refs #388

[github-actions]

🌿 Preview

https://signalwire-preview-docs-613.docs.buildwithfern.com/docs

---

View workflow run