submission paging, compact search view, upstream error classification
Adds two additive capabilities and improves error fidelity, all
backward-compatible.
- hn_get_user: submissionOffset pages through a full submission history beyond the first page (#12)
- hn_search_content: view ("full" | "compact") drops duplicated body text per hit while keeping metadata and matched terms (#15)
- Upstream HTTP failures from HN/Algolia now classify onto a typed reason and recovery hint instead of a raw fetch error, across all four tools (#16)
- Reconciled docs/design.md with the as-built tool surface