feat: add Judilibre, BOFIP and BODACC legal connectors

[dorushugo]

Summary

Adds three new legal data sources as AI tools, implementing connectors listed in docs/feature-status.md as planned but not yet available:

• Judilibre (judilibre_search + judilibre_decision): search and retrieve full-text decisions from Cour de cassation and courts of appeal via the PISTE gateway. Reuses the existing piste connector credentials.
• BOFIP (bofip_search): search French tax doctrine (Bulletin Officiel des Finances Publiques) via the PISTE/Légifrance CIRC fund.
• BODACC (bodacc_search): search commercial announcements (company creation, modification, liquidation, collective proceedings) from the DILA open data API. No authentication required — always available.

Architecture decisions

• Judilibre and BOFIP are gated behind active.includes("piste") since they reuse the existing PISTE OAuth credentials
• BOC is always available (open data, no auth)
• Added a generic odsSearch helper for OpenDataSoft APIs (reusable for future connectors)
• Extended piste.ts with pisteGet and pistePost helpers to support both HTTP methods

What's NOT included (and why)

• EUR-Lex: The Cellar SPARQL endpoint is currently unstable/in maintenance. Will add in a follow-up PR when the API is reliable again.
• Infogreffe: Recently closed public access to record-level data (returns 403). Can be revisited if they reopen or provide an API key mechanism.

Test plan

• Unit tests for Judilibre (search + get decision) with mocked PISTE OAuth flow
• Unit tests for BODACC with mocked OpenDataSoft responses
• Live validation: BODACC API returns correct data structure
• All 220 existing tests still pass (zero regression)
• TypeScript compiles cleanly (tsc --noEmit)