feat(ecu): Add Ecuador cédula validator

[AngusHsu]

Description

Add support for Ecuador Cédula de Identidad.

Parent Epic

#14 - Add support for new countries

Ecuador Cédula Format

• 10 digits
• Format: PPNNNNNNND
• PP: Province code (01-24)
• NNNNNNN: Sequential number
• D: Check digit (mod 10)

Tasks

• Research and verify format
• Create src/countries/ecu/ directory
• Implement Cedula validator class
• Implement validate() with checksum
• Implement parse() function
• Add to main dispatcher
• Add to getCountryIdFormat()
• Write comprehensive tests (80%+ coverage)

Acceptance Criteria

• Validation works correctly
• Province code validated
• Test coverage 80%+

Labels

enhancement, new-country, ecuador