Remove Estonian BO history branch after register access change

[StephenAbbott]

Summary

Access to beneficial-ownership data in the Estonian Business Register (e-äriregister) changes on 10 July 2026 an unknown future date. The Time Machine's Estonian BO-history events were deliberately isolated in the codebase so the whole branch can be dropped cleanly when that date arrives. This is a well-scoped maintenance task — a good first contribution.

What to remove

• _bo_events() in backend/opencheck/timeline/ariregister.py — the function that maps tegelikudKasusaajad_v2 (beneficial-owner history) responses into ChangeEvents. It is deliberately self-contained.
• The tegelikudKasusaajad_v2 SOAP call in AriregisterAdapter.fetch_timeline_data() (backend/opencheck/sources/ariregister.py).
• Any related fixtures/tests in backend/tests/ that exercise the BO branch of the Estonian timeline.

What to keep

• The rest of fetch_timeline_data() — the detailandmed_v2 registry-card history (officers, and shareholders on the register card since Sept 2023) is unaffected.
• The live-lookup web scraper path (company_print_json) is entirely separate — do not touch.

Verify

• python3 -m pytest from backend/ stays green.
• An Estonian entity lookup with the Time Machine enabled still shows registry-card history events, minus BO events.
• Check whether the register offers a replacement/authorised access route worth documenting in docs/sources.md — if the new regime allows some BO access, note it as a follow-up rather than reimplementing here.

Background

CLAUDE.md § "Estonian adapter (ariregister) — hard-won constraints" documents the SOAP history path and this planned removal ("BO access changes 10 July 2026. BO events are deliberately isolated in _bo_events() … so the whole branch can be dropped then").

[StephenAbbott]

Details from Estonia's ariregister on Change in access to beneficial ownership data from 10 July 2026: https://abiinfo.rik.ee/en/node/366/

Changes to the GENERAL TERMS AND CONDITIONS FOR USE OF INQUIRY SYSTEMS from 10.07.2026: https://abiinfo.rik.ee/en/node/367/

[StephenAbbott]

Reopening — Estonia postponed the restriction on its start date.

The Ministry of Finance announced on 10 July (the day the change was due to take effect) that the switch to legitimate-interest access is postponed while the draft regulation is revised after consultation feedback; current public access rules remain in place and no new date has been announced: https://news.err.ee/1610074816/estonia-s-regulation-to-hide-beneficial-owners-postponed

The removal shipped in 77e7b65 has been reverted in a277aec: _bo_events() and the tegelikudKasusaajad_v2 SOAP call are restored, Estonian BO history is back in the Time Machine, and docs/CLAUDE.md describe BO coverage as available again. Two things were kept from the removal commit as insurance for the eventual new date: the _HTML_BO_WITHDRAWN degradation fixture + tests (built from the auth-prompt markup observed live during the aborted changeover), and this issue itself — 77e7b65 now serves as the exact recipe for what to re-apply when Estonia announces the new effective date.

This issue is now blocked on Estonia announcing that date. When it lands: re-apply the removals from 77e7b65, re-add the EE entry to eu_bo_access.json with the new restricted_from date (it was removed in a277aec because the postponement made the 2026-07-10 date false), and re-verify live.