SevApp Starter - Updated

What's new:
- SEPA validation helper: src/SepaValidator.php. Place official SEPA XSD (e.g. pain.001.001.03.xsd) into assets/sepa/ to enable schema validation.
  Optionally install a composer SEPA library and update SepaValidator to use it.

- Web UI for Bank Imports & Manual Reconciliation:
  public/bank_imports.php
  Upload CSV or OFX, preview transactions and manually create payments (optionally link to invoice).

- Subdomain-based tenant detection:
  src/Tenant.php now attempts to set tenant based on subdomain (tenant.example.com). Create tenants with 'subdomain' set in the DB.

Deployment:
1) Edit config.php for DB and base_url.
2) composer install (to use dompdf/phpmailer or additional libraries).
3) Import init.sql and set a secure admin password hash in the users table.
4) Place official SEPA XSD in assets/sepa/pain.001.001.03.xsd to enable validation.
5) Ensure uploads/ is writable for bank imports.

Security notes:
- This starter is for self-hosting; secure your installation (HTTPS, correct permissions, remove debug modes).
- Consider adding CSRF protection, input sanitization and rate-limiting for API routes.


- Tenant subdomain: sev.titech.at (will automatically select tenant 'Default Tenant').