Add STJ + CARF real ruling-text tools; TST client confirmed live but not wired

- br_search_case_stj / br_get_case_stj: real full-text acordao (ementa +
  decisao prose) from the STJ CKAN open-data portal, bounded scan of recent
  monthly snapshots per orgao julgador. Coverage starts May 2022.
- br_get_case_carf: real full-text CARF tax-appeal acordao by exact docket
  or decision number, against the public acordaos.economia.gov.br Solr
  index. No search tool: CARF's own full-text field returns zero hits for
  common terms on live probing.
- Planalto (REFLEGIS) re-checked live: still no structured API, connection
  times out with zero bytes to a plain HTTP client (bot-challenge/WAF).
  Existing rejection in README/SOURCES preserved and extended.
- TST: found the real backend (jurisprudencia-backend2.tst.jus.br, via the
  frontend's own config.json) with working doc-type filter + pagination,
  but no confirmed exact-match/process-number contract. Client, models,
  citations and tests are kept and passing; no MCP tool ships this release
  to avoid a browse-only "search" that can't reliably retrieve one case.
- Querido Diario checked live: Cloudflare bot-challenge blocks the
  documented gazettes API to a plain client. Not implemented.

Version 0.4.0 -> 0.5.0. Ruff clean, 20/20 tests passing (offline fixtures +
live smoke), publication gate PASS.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>