feat(llm-obs): export annotated interaction data

[hannahqjiang]

Summary

Add a Pup command that exports an annotated LLM Observability interaction together with its complete interaction data.

Changes

• Add pup llm-obs annotations export with queue ID or exact-name resolution
• Fetch and combine every cursor page while preserving stored interaction content
• Support standard stdout formatting plus atomic JSON and JSONL file exports
• Forward validated request-routing headers for Rapid test drives
• Reuse the shared authenticated raw HTTP transport
• Document the command and add positive and negative coverage

Testing

• cargo test -- --test-threads=1 (1,834 passed)
• cargo clippy -- -D warnings
• cargo fmt --all -- --check
• git diff --check