[Core] Quantum Painter - LVGL Integration (#18499)

Co-authored-by: Nick Brassel <nick@tzarc.org>

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+# Quantum Painter LVGL Integration :id=lvgl
+
+LVGL (Light and Versatile Graphics Library) is an open-source graphics library providing everything you need to create an embedded GUI for your board with easy-to-use graphical elements.
+
+LVGL integrates with [Quantum Painter's](quantum_painter.md) API and drivers to render to the display, the hardware supported by Quantum Painter is also supported by LVGL.
+
+?> Keep in mind that enabling the LVGL integration has a big impact in firmware size, it is recommeded to use a supported MCU with >256 kB of flash space.
+
+To learn more about LVGL and how to use it please take a look at their [official documentation](https://docs.lvgl.io/8.2/intro/)
+
+## Enabling LVGL :id=lvgl-enabling
+To enable LVGL to be built into your firmware, add the following to `rules.mk`:
+
+```make
+QUANTUM_PAINTER_ENABLE = yes
+QUANTUM_PAINTER_DRIVERS = ......
+QUANTUM_PAINTER_LVGL_INTEGRATION = yes
+```
+To configure the Quantum Painter Display Drivers please read the [Quantum Painter Display Drivers](quantum_painter.md#quantum-painter-drivers) section.
+
+## Quantum Painter LVGL API :id=lvgl-api
+
+### Quantum Painter LVGL Attach :id=lvgl-api-init
+
+```c
+bool qp_lvgl_attach(painter_device_t device);
+```
+
+The `qp_lvgl_attach` function is used to set up LVGL with the supplied display, and requires an already configured display.
+
+```c
+static painter_device_t display;
+void keyboard_post_init_kb(void) {
+    display = qp_make_.......;         // Create the display
+    qp_init(display, QP_ROTATION_0);   // Initialise the display
+    
+    if (qp_lvgl_attach(display)) {     // Attach LVGL to the display
+        ...Your code to draw           // Run LVGL specific code to draw
+    }
+}
+```
+To init. the display please read the [Display Initialisation](quantum_painter.md#quantum-painter-api-init) section.
+
+!> Attaching LVGL to a display means LVGL subsequently "owns" the display. Using standard Quantum Painter drawing operations with the display after LVGL attachment will likely result in display artifacts.
+### Quantum Painter LVGL Detach :id=lvgl-api-init
+
+```c
+void qp_lvgl_detach()
+```
+
+The `qp_lvgl_detach` function stops the internal LVGL ticks and releases resources related to it.
+
+## Enabling/Disabling LVGL features :id=lvgl-configuring
+
+You can overwrite LVGL specific features in your `lv_conf.h` file.