fix(import): raise statement_timeout on import_sie_journal_entries to 290s (#1101)

A production Fortnox migration failed with "SIE-verifikationer kunde
inte importeras atomiskt: canceling statement due to statement
timeout": the atomic import RPC (20260712150000) inherits the 8s
authenticator statement_timeout, so any real-world multi-year SIE file
exceeds it and the whole import is cancelled and rolled back. Same
failure class as 20260629160100 (replace_sie_import / undo_sie_import);
same fix, a function-scoped statement_timeout of 290s sitting under the
calling routes' maxDuration = 300 ceiling.

Migration 20260721144311 is already applied to prod (proconfig verified
carrying statement_timeout=290s); the committed file is byte-identical
under the same version. The new pg-real ratchet pins the config on all
three SIE RPCs because CREATE OR REPLACE FUNCTION silently drops
ALTER FUNCTION settings.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

tests/pg/sie-rpc-statement-timeout.pg.test.ts

@@ -0,0 +1,42 @@
+import { describe, expect, it } from 'vitest'
+import { getPool } from './setup'
+
+/**
+ * The SIE import/replace/undo RPCs each run an entire file's work in one
+ * statement, so each carries a function-scoped statement_timeout (migrations
+ * 20260629160100 and 20260721144311); without it they inherit the 8s
+ * authenticator timeout and any real-world multi-year migration is cancelled
+ * with "canceling statement due to statement timeout".
+ *
+ * CREATE OR REPLACE FUNCTION silently drops settings attached via
+ * ALTER FUNCTION ... SET, so a future redefinition of any of these functions
+ * would revive the bug unless the SET is carried along. This ratchet runs
+ * after full migration replay in CI and pins the config.
+ */
+
+const TIMEOUT_PROTECTED_FUNCTIONS = [
+  'import_sie_journal_entries',
+  'replace_sie_import',
+  'undo_sie_import',
+]
+
+describe('SIE RPC statement_timeout config', () => {
+  it.each(TIMEOUT_PROTECTED_FUNCTIONS)(
+    '%s carries a function-scoped statement_timeout of 290s',
+    async (functionName) => {
+      const { rows } = await getPool().query<{ proconfig: string[] | null }>(
+        `SELECT p.proconfig
+         FROM pg_proc p
+         JOIN pg_namespace n ON n.oid = p.pronamespace
+         WHERE n.nspname = 'public' AND p.proname = $1`,
+        [functionName],
+      )
+      expect(rows, `${functionName} should exist exactly once in public`).toHaveLength(1)
+      expect(
+        rows[0].proconfig ?? [],
+        `${functionName} lost its statement_timeout: re-add "SET statement_timeout = '290s'" ` +
+          'to the CREATE OR REPLACE FUNCTION statement that redefined it',
+      ).toContain('statement_timeout=290s')
+    },
+  )
+})