appEvents.path dead column — drop or populate (never-populated query trap)

appEvents has a plain path COLUMN populated on 0/7860 rows ever (measured db-venus-cc 2026-07-31, tag db-venus-cc-ms8gy89cb5x5): an always-NULL column that reads as an answer is a query trap (confident empty set). Decide: drop it, or start populating it from writers. Context: venus detail-key path variants (urlPath/refererPath/requestedPath/routePath) are writer-side sprawl only — zero read surfaces filter on them; all readers key on route (2758 non-null, live). No reader fix needed; this WI is the single hygiene remainder. DDL goes via db-venus-cc; audit pre-apply review if drop chosen. Audit concurrence: audit-venus-ca-ms8gyfbueby2.