WS4 Parts A/B/C: Disclosure Review rework + five new UK workflow templates

Part A (remaining 2 rows for this file): UK spelling fixes in the Change of
Control Review column prompts (summarise).

Part B (DECIDED, MIGRATION_SPEC §6.1): renames "E-Discovery Review" to
"Disclosure Review", reframes it around CPR Part 31 / PD 57AD, and splits the
single "Privileged?" column into three: Legal Advice Privilege, Litigation
Privilege, and Without Prejudice, each Yes/No + basis with uncertainty noted
explicitly. The id is deliberately kept as "builtin-ediscovery" rather than
renamed: backend/schema.sql's hidden_workflows.workflow_id is a free-text
column keyed on this exact string, so renaming would silently un-hide the
workflow for any user who had previously hidden it (see code comment at the
template definition, and docs/BUILD_LOG.md for the full rationale).

Part C adds five new UK workflow templates: English-law SPA Review (tabular,
Corporate), Commercial Lease Review - LTA 1954 (tabular, Real Estate, with a
dedicated security-of-tenure / s.38A contracting-out column and a 1954 Act
red-flags column), TUPE Analysis (assistant, Employment, structured reg
3/4/7/13-15 analysis), Employment Contract vs Statutory Minima (tabular,
Employment, contractual term vs statutory floor per column), and Companies
House Due-Diligence Snapshot (assistant, Corporate, names the CH tools and
instructs the model not to invent register data when they're unavailable).

All statutory references used in these templates are real, resolvable
citations (verified live against legislation.gov.uk - see evals/cases/cit-*
added in a following commit). No case-law citations anywhere in the new
content, per the Find Case Law deferral.

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