Support RGB888 raw images and validate raw file size

[Inter-Raptor]

Motivation

• Some large .raw assets (e.g. boot/home backgrounds) were displayed garbled because displayDrawRAW assumed 2 bytes/pixel RGB565 format and did not validate file contents against expected size.
• The goal is to fail early on format/dimension mismatches and support RGB888 raw images so correctly-exported assets render properly.

Description

• Added file-size validation in displayDrawRAW to detect whether the file matches the expected RGB565 (2 bytes/pixel) or RGB888 (3 bytes/pixel) bytecount for the given width/height.
• Implemented conditional per-pixel reads for both RGB565 and RGB888, converting RGB888 pixels to 16-bit with lcd.color565(r,g,b), and adjusted row skipping to use the bytes-per-pixel value.
• Improved serial diagnostics to log unexpected sizes and the detected input format, and preserved existing memory/error handling and clipping behavior.

Testing

• Searched the codebase for raw image usage with rg to confirm all callers of displayDrawRAW (launcher_ui.cpp) and inspected the modified function with nl/sed to verify the changes.
• Reviewed the resulting diff to ensure the new logic replaces the old per-pixel read and updates row skipping and log messages.
• No hardware build or on-device runtime display test was executed in this environment, so runtime verification on a device is still required to confirm correct rendering of boot.raw / home.bg.raw assets.

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Codex Task