Palette Test

Tests the 8-bit framebuffer with "coder colors" palette. Shows all 256 colors in a 16×16 grid, each color as a 4×4 pixel block (64×64 pixels total).

The palette is organized as 64 rainbow hues × 4 brightness levels:

• Rows 0-3: Brightness 0 (darkest), hues 0-63
• Rows 4-7: Brightness 1
• Rows 8-11: Brightness 2
• Rows 12-15: Brightness 3 (brightest)