Migrate the API to native ESM and vitest; pin Node 26

Prep PR for the admin auth module (docs/plan-admin-auth.md step 1).
better-auth 1.7 ships ESM only, so the API moves off CommonJS:

- "type": "module", module nodenext, target ES2024, .js suffixes on all
  relative imports, require('mariadb'|'cors') replaced by imports, and
  export= packages (winston, app-root-path, bcrypt) consumed via default
  imports. The logger now uses appRoot.path explicitly.
- TypeScript 5.9, @types/node 26, tslint removed. Node 26 pinned via
  engines and .nvmrc (Plesk runs 26).
- Jest 28 + ts-jest replaced by vitest 5. Eight test files depend on
  hoisted module mocks with static imports and resetModules + require,
  which Jest's ESM mode does not support; vitest keeps them nearly
  verbatim. Coverage via @vitest/coverage-v8 (lcov), Sonar generic report
  via vitest-sonar-reporter, so sonar-project.properties is unchanged.
  vitest.config.ts sets FEEDBACK_IP_SALT so the suite passes without a
  local .env.
- dotenv 8 -> 16 and axios 0.24 -> 1.x: their old typings are not
  resolvable under nodenext.
- autoCommit: false dropped from the pool configs; it is not a mariadb
  connector option and was silently ignored.

tsc clean, 96/96 tests green, compiled app boots and serves /, /docs and
CORS under Node ESM.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

test/tickets/redemptions.admin.resend.test.ts

@@ -3,21 +3,22 @@
 // exercised here; the shared send/record logic is covered by
 // confirmation-email.test.ts.
 
-jest.mock('../../src/models/tickets/Tickets.db', () => ({
-	NachklangTicketsDB: {getConnection: jest.fn()}
+import {vi, describe, it, expect, beforeEach, type Mock} from 'vitest';
+vi.mock('../../src/models/tickets/Tickets.db.js', () => ({
+	NachklangTicketsDB: {getConnection: vi.fn()}
 }));
-jest.mock('../../src/models/tickets/tickets.confirmation-email', () => ({
-	sendRedemptionConfirmation: jest.fn(),
-	recordConfirmationEmailResult: jest.fn()
+vi.mock('../../src/models/tickets/tickets.confirmation-email.js', () => ({
+	sendRedemptionConfirmation: vi.fn(),
+	recordConfirmationEmailResult: vi.fn()
 }));
 
-import {NachklangTicketsDB} from '../../src/models/tickets/Tickets.db';
-import {recordConfirmationEmailResult, sendRedemptionConfirmation} from '../../src/models/tickets/tickets.confirmation-email';
-import {resendRedemptionConfirmation} from '../../src/models/tickets/admin/redemptions.admin.service';
+import {NachklangTicketsDB} from '../../src/models/tickets/Tickets.db.js';
+import {recordConfirmationEmailResult, sendRedemptionConfirmation} from '../../src/models/tickets/tickets.confirmation-email.js';
+import {resendRedemptionConfirmation} from '../../src/models/tickets/admin/redemptions.admin.service.js';
 
-const mockGetConnection = NachklangTicketsDB.getConnection as jest.Mock;
-const mockSend = sendRedemptionConfirmation as jest.Mock;
-const mockRecord = recordConfirmationEmailResult as jest.Mock;
+const mockGetConnection = NachklangTicketsDB.getConnection as Mock;
+const mockSend = sendRedemptionConfirmation as Mock;
+const mockRecord = recordConfirmationEmailResult as Mock;
 
 const ACTIVE_ROW = {
 	redemption_id: 5,
@@ -34,15 +35,15 @@ const ACTIVE_ROW = {
 
 // getRedemption issues: 1) SELECT redemptions, 2) SELECT redemption_guests
 const connFor = (redemptionRows: any[], guestRows: any[] = []) => ({
-	query: jest
+	query: vi
 		.fn()
 		.mockResolvedValueOnce(redemptionRows)
 		.mockResolvedValueOnce(guestRows),
-	end: jest.fn().mockResolvedValue(undefined)
+	end: vi.fn().mockResolvedValue(undefined)
 });
 
 beforeEach(() => {
-	jest.clearAllMocks();
+	vi.clearAllMocks();
 	mockSend.mockResolvedValue(true);
 });