UR-Nexus 1.87.2

• Fixed Claude API requests failing with HTTP 400 because UR automatically sent
  the invalid ur-20250219 beta header. External providers no longer inherit
  hosted-service beta flags. Documented manual-thinking and fast-mode feature
  headers remain available, and explicit Anthropic beta opt-ins are preserved.
• Stopped adding a default temperature to Claude requests that omit thinking,
  allowing current models such as Opus 5.5 to use their supported defaults.
• Fixed response logging accepting only Web Headers: native HTTP response
  headers now work too, so a successful model reply cannot fail in logging.
• Added a strict local HTTP regression through the complete query pipeline,
  covering multiple Claude models, streaming, token counts and feature betas.