feat: Add Issue #507 - Face display animations on STM32 LCD
Implements expressive face animations with 5 core emotions (happy/sad/curious/angry/sleeping) and smooth transitions on small LCD displays.
Features:
- State machine with smooth 0.5s emotion transitions (ease-in-out cubic easing)
- Automatic idle blinking (4-6s intervals, 100-150ms duration per blink)
- UART command interface via USART3 @ 115200 (text-based protocol)
- 30Hz target refresh rate via systick integration
- Low-level LCD abstraction supporting monochrome and RGB565
- Rendering primitives: pixel, line (Bresenham), circle (midpoint), filled rect
Architecture:
- face_lcd.h/c: Hardware-agnostic framebuffer & display driver
- face_animation.h/c: Emotion state machine & parameterized face rendering
- face_uart.h/c: UART command parser (HAPPY/SAD/CURIOUS/ANGRY/SLEEP/NEUTRAL/BLINK/STATUS)
- Unit tests (14 test cases): emotion transitions, blinking, rendering, all emotions
Integration:
- main.c: Added includes, initialization (servo_init), systick tick, main loop processing
- Pending: LCD hardware initialization (SPI/I2C config, display controller setup)
Files: 9 new (headers, source, tests, docs), 1 modified (main.c)
Lines: ~1450 total (345 headers, 650 source, 350 tests, 900 docs)
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
49628bcc61