refactor: enforce enum machine codes

Use owner enums for error and T-Bank protocol values with ESLint regression checks.

Preserve open wire fallbacks and keep protocol imports independent of DI and Prisma.

Verified npm ci, verify, 226 unit tests, 262 isolated e2e tests and unchanged OpenAPI.

test/eslint-config.cjs

@@ -61,3 +61,27 @@ test('numeric literals require names, including previously ignored numbers and b
     assert.ok(!named.messages.some(({ ruleId }) => ruleId === '@typescript-eslint/no-magic-numbers'), literal);
   }
 });
+
+// Single-use codes must be caught too; fixture literals remain independent wire assertions.
+test('machine codes require enum members without banning ordinary text or Prisma selects', async () => {
+  const eslint = new ESLint();
+  const filePath = 'src/main.ts';
+  for (const code of ['export function check(code: string) { return code === "one-off-code"; }', 'export const result = `MOEX_UNAVAILABLE`;', 'export const result = { code: "one-off-code" };', 'export const result = { "errorCode": "one-off-code" };', 'export const result = { code: `dynamic-${Date.now()}` };', 'export const result = "MOEX_UNAVAILABLE";', 'export const result = ["INSTRUMENT_ID_TYPE_FIGI"];', 'export const result = { OPERATION_TYPE_COUPON: "income" };']) {
+    const [result] = await eslint.lintText(code, { filePath });
+    assert.equal(result.fatalErrorCount, 0, code);
+    assert.ok(result.messages.some(({ ruleId }) => ruleId === 'no-restricted-syntax'), code);
+  }
+  for (const code of [
+    'enum Code { Unavailable = "MOEX_UNAVAILABLE" } export const result = { code: Code.Unavailable };',
+    'export const select = { code: true, errorCode: true };',
+    'export const label = "Please try again"; export const key = "JWT_SECRET";',
+  ]) {
+    const [result] = await eslint.lintText(code, { filePath });
+    assert.equal(result.fatalErrorCount, 0, code);
+    assert.ok(!result.messages.some(({ ruleId }) => ruleId === 'no-restricted-syntax'), code);
+  }
+  const [fixture] = await eslint.lintText('export const result = { code: "MOEX_UNAVAILABLE" };', { filePath: 'src/integrations/moex/moex.client.spec.ts' });
+  assert.ok(!fixture.messages.some(({ ruleId }) => ruleId === 'no-restricted-syntax'));
+  const [comparison] = await eslint.lintText('enum Code { Ready = "ready" } export function check(code: Code) { return code === "ready"; }', { filePath });
+  assert.ok(comparison.messages.some(({ ruleId }) => ruleId === '@typescript-eslint/no-unsafe-enum-comparison'));
+});