Raspberry Pi Pico Keypad Lock (4x4 Keypad + I2C LCD + Servo)

A 4-digit code opens the door, and three wrong tries mean a 30 second wait! The **Raspberry Pi Pico** checks the PIN typed on a **4x4 keypad**: if it's right, an **SG90 servo** unlocks and relocks by itself after 5 seconds. An **I2C LCD** shows the stars, the tries left and the countdown, and a **buzzer** beeps on every key. The default PIN is `1234`; change it with the `A` key and the new one is saved to `pin.txt`.