Support adjusting datetime via Serial

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Adding UI sound effect

Refactor timing logic to prevent millis() overflow

Add buzzer module

Implement non-blocking Nixie display and animation

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Implement interrupt-driven clock update with DS3231

Refine datatype in Config File

Implement singleton logger with variadic arguments and log levels

Add .gitignore

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Implement NixieTube class for unified tube control

Add ShiftRegister IC driver support

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