fix(seo): answer Markdown OPTIONS on unknown paths and list every accepted knowledge-base file type

[waleedlatif1]

Summary

• The Markdown 404 route also exports OPTIONS, so an OPTIONS request with Accept: text/markdown to an unknown path gets the Markdown 404 instead of Next's generated 204. Real pages are untouched: the fallback rewrite only runs when no page or route matched
• The comparison pages now count knowledge-base upload types from SUPPORTED_DOCUMENT_EXTENSIONS: 15 file types (adds xls, htm, and yml, which the old list of 12 left out); the Dust FAQ uses the same wording

Type of Change

• Bug fix

Testing

• apps/sim/scripts/test-mcp-host-e2e.ts against a local dev server: 21/21, with the POST check extended to OPTIONS; removing the OPTIONS export turns it red (204)
• apps/sim/scripts/test-landing-seo-e2e.ts: 13/13; /comparisons/dust renders "15 file types"
• OPTIONS /pricing returns the same 400 with and without Accept: text/markdown
• bun run lint, check:source-conventions, check:comment-hygiene, check:unused-exports, check:test-patterns

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing (new tests pass the test-audit authoring gate)
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

[vercel]

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1 Skipped Deployment

Project	Deployment	Actions	Updated
docs	Skipped		Oct 16, 2026 2:20am UTC

[cubic-dev-ai]

No issues found across 4 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

_{Turn on auto-fix | Re-trigger cubic}

[greptile-apps]

Confidence Score: 5/5

[Low impact] The PR appears safe to merge.

Summary

Adds Markdown 404 responses for OPTIONS requests to unknown paths and corrects the knowledge-base file list.

• Unknown Markdown requests get the right 404 for OPTIONS.
• Comparison pages now list all 15 knowledge-base file types.

_{Reviews (1) · Last reviewed commit: "fix(seo): answer Markdown OPTIONS on unk..." · Reviewed by Greptile}