inspect: accept runner-style structured trail findings

Use the existing Trail PR Review runner output shape as the preferred trail posting format: if the judge output ends with a JSON object containing comments, convert those comments directly to native trail review findings, preserving severity, confidence, and line/range/file locations.

Keep the markdown fallback for custom or human-readable prompts, but enrich split bullets with inferred severity and file:line anchors when possible. Also nudge the judge prompt to put one issue per bullet with severity and file:line pointers so trail output is cleaner even before the fallback runs.