Migration 0008 + ORM model for payslip_ingest.rsu_vest_events.
Purpose: broker-sync (separate repo) will parse Schwab "Release
Confirmation" emails and populate this table, enabling Panel 15 of
the UK payslip dashboard to reconcile:
payslip.rsu_vest ↔ SUM(rsu_vest_events.gross_value_gbp)
RSU-attributed PAYE ↔ SUM(rsu_vest_events.tax_withheld_gbp)
Schema carries both the raw USD figures (fmv_at_vest_usd,
tax_withheld_usd, shares_*) and the GBP-translated values
(gross_value_gbp, tax_withheld_gbp) plus the FX rate used — the
dashboard joins on GBP, audits keep USD.
Idempotent on `external_id` — broker-sync emits a stable
`schwab:{date}:{ticker}:VEST:{shares_vested}` for each vest event.
The broker-sync postgres sink that writes here is pending a real email
fixture (current parser is heuristic-only) and a cross-service DB grant
for broker-sync's K8s ServiceAccount. Follow-up under code-860.
Part of: code-860
3a62a38069