Cover business interests via a proper continuity instrument

Same gap as land parcels: business assets were routed into the generic
trust fields (trustee/successor/beneficiaries), which don't fit — a
business needs a continuity instrument, not a trustee holding title.

New "business-continuity" channel in Nomination Registry, modelled on the
digital-waqif docs repo's own business-succession framework (Clause 9):
- Structure selector (sole proprietorship / partnership / company). Sole
  proprietorship surfaces an explicit warning: it legally dies with the
  owner, so the only fast-path options are converting to a company or
  dedicating as a waqf-owned enterprise.
- Instrument selector: partnership continuation clause, shareholder
  buy-sell agreement (the standard fast-path for company shares, often
  Takaful-funded), or a direct redirect to Family Waqf Designator for a
  waqf-owned enterprise (nothing duplicated here — reuses that module).
- Dedicated business-continuity-draft.txt export, same treatment as the
  trust deed and waqfiyya exports.
- Death Trigger packet text updated with the business-specific execution
  action (execute buy-sell / continuation clause, file Takaful claim if
  funded — a private agreement between owners, not a probate filing).

e2e-business.cjs: new suite covering exposed->warning->instrument
selection->export->100% coverage->execution packet, plus the
waqf-enterprise redirect disabling the Add button. 10/10 passing.
Re-verified e2e-uat.cjs (32/32), e2e-fastpath.cjs (16/16), and
e2e-trust.cjs (12/12) — 70/70 total, no regressions.

src/lib/CoverageDashboard.svelte

@@ -14,6 +14,7 @@
     takaful: 'Takaful / insurance nomination',
     'bank-mandate': 'Bank death mandate',
     trust: 'Trust / nominee holding',
+    'business-continuity': 'Business continuity instrument',
     'hibah-flagged-capped': 'Hibah flagged (marad al-mawt) — capped, partially exposed',
     none: 'Not covered — exposed to Faraid/probate'
   };