fix(salary): stop RLS from failing vab/parental absence registration (#1568)

Migration 20260517135000 rewrote the franvaro-specifikationsnummer trigger
functions to insert audit rows into salary_absence_franvaro_audit, a table
with RLS enabled and zero policies, while leaving the functions SECURITY
INVOKER (its comment claimed implicit SECURITY DEFINER, which is false in
Postgres). Every vab/parental insert from role authenticated (dashboard
absence POST, web /pending approval, in-app Assistenten chat) then failed
with 42501, surfaced as a generic 500, and left no diagnosable trace.

- New migration 20260813120000: ALTER both trigger functions to SECURITY
  DEFINER with search_path pinned to public, pg_temp. No RLS policy is added
  on the audit table: trigger/service-only writes stay the design intent.
- mapInsertError: 42501 now maps to the new bilingual DB_PERMISSION_DENIED
  code instead of INTERNAL_ERROR, and 23514 is split so only the 24h-cap
  trigger's 'Total tid' message becomes ABSENCE_HOURS_CONFLICT; other CHECK
  violations map to VALIDATION_ERROR.
- commitRegisterAbsence/commitDeleteAbsence: log the underlying PG details
  and persist the sanitized structured code in result_data.error_code so the
  next failure is traceable from the op row.
- Dashboard absence route: only ABSENCE_HOURS_CONFLICT passes details.message
  through to the client; every other code shows the registry Swedish message
  instead of raw Postgres text.
- New pg-real regression test locks the authenticated-role parental/vab
  insert path, the shared per-month specnummer sequence, the audit rows, and
  idempotent upsert retries.

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

lib/pending-operations/commit.ts

@@ -4982,9 +4982,23 @@ async function commitRegisterAbsence(
       includeWeekends: (params.include_weekends as boolean | undefined) ?? false,
     })
     if (!result.ok) {
+      // The user-facing message is generic Swedish; without this log the
+      // underlying PG error (e.g. the franvaro audit-trigger RLS denial that
+      // caused five untraceable 500s, feedback 2026-08-13) leaves no trace.
+      // pgDetails, not details: `details` is the logger record's own field
+      // for non-object args and would be swallowed by the pretty emitter.
+      createLogger('commit/register_absence').error('register_absence commit failed', {
+        code: result.code,
+        pgDetails: result.details,
+        employeeId,
+        absenceType,
+        from,
+        to,
+      })
       const entry = getErrorEntry(result.code)
       return {
         error: entry?.message_sv ?? `Kunde inte registrera frånvaron: ${result.code}`,
+        errorCode: result.code,
         status: entry?.httpStatus ?? 500,
       }
     }
@@ -5081,9 +5095,19 @@ async function commitDeleteAbsence(
       absenceType: (params.absence_type as string | undefined) || undefined,
     })
     if (!result.ok) {
+      // Same diagnosability treatment as commitRegisterAbsence: keep the PG
+      // error in the logs and the registry code on the op row.
+      createLogger('commit/delete_absence').error('delete_absence commit failed', {
+        code: result.code,
+        pgDetails: result.details,
+        employeeId,
+        from,
+        to,
+      })
       const entry = getErrorEntry(result.code)
       return {
         error: entry?.message_sv ?? `Kunde inte ta bort frånvaron: ${result.code}`,
+        errorCode: result.code,
         status: entry?.httpStatus ?? 500,
       }
     }