Scrape Markdown conversion corrupts application/vnd.api+json responses

Problem

Scrape's Markdown conversion treats JSON response content types inconsistently. A response served as application/json is returned verbatim inside a JSON code fence, while the same kind of JSON served as application/vnd.api+json is Markdown-escaped and no longer parses as JSON.

Reported behavior

For application/vnd.api+json responses, brackets and underscores are escaped, backslash line continuations are introduced, and newlines can appear inside strings. This was reported on public Regulations.gov API responses and reproduced on September 16, 2026 using the core Scrape API through CLI 1.23.4-alexandria-beta.5.

Reproduction

1. Scrape a publicly reachable endpoint that returns a JSON object with Content-Type: application/vnd.api+json, requesting Markdown.
2. Attempt to parse the returned content as JSON after removing a code fence if present.
3. Compare with an endpoint serving the same body as application/json.

The vendor JSON response should retain its original JSON syntax, matching the handling of application/json.

Suggested fix

Recognize JSON media types with a +json suffix and preserve the body verbatim instead of passing it through Markdown escaping.

Priority: P4 / backlog.