Add support for Lao language

[tomivm]

Description

Add support for the Lao language (lo) to expand Cboard's accessibility to Lao-speaking users.

Tasks

• Add Lao language code and name to the App Languages constant
• Ensure proper RTL/LTR handling for Lao script
• Update language selection UI to include Lao

Additional Information

• Language code: lo
• Language name in English: Lao
• Native name: ລາວ
• ISO 639-1 code: lo

Benefits

This addition will make Cboard more accessible to Lao-speaking users, particularly beneficial for AAC users in Laos and Lao-speaking communities worldwide.