feat: yubikey mock and touch prompting

[millerjason]

Summary:

• Adds challenge-response provider abstraction to enable pluggable authentication backends (hardware YubiKey, mock implementations, future smart cards, etc.) via the new ChallengeResponseProvider ABC
• Implements MockYubiKey for testing YubiKey functionality without physical hardware, supporting both zero-secret (for basic testing) and custom secret configurations
• Adds touch prompting for YubiKey operations that require physical touch, improving user experience during challenge-response authentication (library would previously hang without notice)
• Improves error hierarchy by introducing ChallengeResponseError as base class with YubiKeyError as implementation-specific subclass
• Enhances test coverage with comprehensive tests for both hardware (when available) and mock YubiKey scenarios (always)

Key Changes:

• src/kdbxtool/security/challenge_response.py (new): Abstract base class for challenge-response authentication
• src/kdbxtool/security/yubikey.py: Split into HardwareYubiKey and MockYubiKey classes
• src/kdbxtool/database.py: Refactored to use provider interface instead of direct YubiKey parameters
• src/kdbxtool/exceptions.py: Added ChallengeResponseError base class in hierarchy
• tests/test_yubikey.py: Updated with extensive mock-based tests (allows testing without hardware)
• tests/test_yubikey_hardware.py: Separated hardware-specific tests

Minor:

• Update init.py and uv versions to 0.1.5 to match github release version.