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>

src/models/tickets/admin/redemptions.admin.service.ts

@@ -1,8 +1,8 @@
-import {NachklangTicketsDB} from '../Tickets.db';
-import {getEventTicketState} from '../tickets.capacity';
-import {recordConfirmationEmailResult, sendRedemptionConfirmation} from '../tickets.confirmation-email';
-import {AuditLogEntry, RedemptionSummary} from '../tickets.interface';
-import {isValidEmail} from '../tickets.validation';
+import {NachklangTicketsDB} from '../Tickets.db.js';
+import {getEventTicketState} from '../tickets.capacity.js';
+import {recordConfirmationEmailResult, sendRedemptionConfirmation} from '../tickets.confirmation-email.js';
+import {AuditLogEntry, RedemptionSummary} from '../tickets.interface.js';
+import {isValidEmail} from '../tickets.validation.js';
 
 const mapRedemptionRow = (row: any, guests: string[]): RedemptionSummary => ({
 	redemptionId: row.redemption_id,