fix(skattekonto): remove the drift email, its event and the unused drift route (#2149)

The nightly skattekonto sync emailed "Skattekontot stämmer inte med
bokföringen" whenever Skatteverket's saldo differed from BAS 1630 by more
than 1 kr, every 24 hours while it lasted. On 2026-09-02 it fired on a
35 842 kr gap that the reconciliation explained to the last krona with 14
unbooked rows, while the Hem notice and the reconciliation page (both
gated on unexplained_difference) said nothing was wrong.

The check shipped in May 2026 (#525) before any in-app skattekonto view
existed; the dashboard tile its comments promise was never built and the
drift API route had no consumer. Since 2026-08-25 the reconciliation page
and the Hem notice are the surface, with one definition of "stämmer inte".

Removed: skattekonto-drift.ts, skattekonto-drift-email.ts, their tests,
the skattekonto.drift_detected event type, the handler registration, the
cron's drift hook, GET /api/extensions/skatteverket/skattekonto/drift, and
the ROPA activity for the mail. The route is dropped from the ungated
extension route allowlist to lock the ratchet. skattekonto_drift_tolerance
stays: the Hem notice reads it. Stale skattekonto_drift_last_alert_at rows
in extension_data are inert.

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

lib/events/types.ts

@@ -213,18 +213,6 @@ export type CoreEvent =
   | { type: 'skattekonto.balance.changed'; payload: { previousBalance: number; currentBalance: number; userId: string; companyId: string } }
   | { type: 'skattekonto.transaction.upcoming'; payload: { transaktionsdatum: string; forfallodatum: string; transaktionstext: string; beloppSkatteverket: number; userId: string; companyId: string } }
   | { type: 'skattekonto.connection.expired'; payload: { reason: 'REFRESH_EXHAUSTED' | 'SESSION_EXPIRED' | 'TOKEN_CORRUPTED'; userId: string; companyId: string } }
-  // Fired when the SKV saldo and GL 1630 sum diverge beyond the configured
-  // tolerance. The drift handler emails the company contact; UI surfaces a
-  // dashboard tile via /api/extensions/skatteverket/skattekonto/drift.
-  | { type: 'skattekonto.drift_detected'; payload: {
-      drift: number                       // SKV saldo - GL 1630 sum (signed)
-      saldoSkatteverket: number
-      glSum1630: number
-      fetchedAt: number                   // ms epoch from the snapshot
-      unbookedCount: number               // skattekonto rows without journal_entry_id ≤ fetchedAt
-      userId: string
-      companyId: string
-    } }
   // Company & account lifecycle
   | { type: 'company.deleted'; payload: { companyId: string; userId: string; archivedAt: string } }
   | { type: 'account.deleted'; payload: { userId: string; deletedAt: string } }