- update `--color-card` to pure/near-pure values in both dark and light themes
- update `--color-button` to more distinct static colors in both themes
- replace variable-based `--color-project-column-bg` with explicit hex values
- update text color palette in dark theme for higher contrast (pure white base)
- update text color palette in light theme for higher contrast (pure black base)
- darken `--color-secondary` in dark theme from #30363d to #1b1b1b
- add `DEFAULT_THEME = octo-auto` example to README
- add theme-octo-dark.css with deep black background and blue accent
- add theme-octo-light.css with white background and blue accent
- add theme-octo-auto.css that switches between light/dark via prefers-color-scheme
- update README with installation instructions, variant descriptions, and customization notes
hykocx