Function sanitizePhoneNumber

sanitizePhoneNumber(phone: string | null | undefined): string
Sanitize phone number by trimming whitespace and removing formatting characters (spaces, hyphens, parentheses, dots) while preserving international leading '+'.
Parameters
- phone: string | null | undefined
Returns string
Example
```
sanitizePhoneNumber('+256 (777) 123-456') // '+256777123456'
sanitizePhoneNumber('0777-123-456') // '0777123456'
```
- Defined in src/utils/phone.ts:9