Pre-scaling (critical fix):
- Add pre-scaling to fit display dimensions (480x800) before dithering
to prevent post-downsampling artifacts that destroy dithering patterns
- Use fixed-point (16.16) math for sub-pixel accurate scaling
- Implement area averaging for smooth downsampling
Dithering improvements:
- Add Atkinson dithering (75% error diffusion) for cleaner results
- Add Floyd-Steinberg dithering option with serpentine scanning
- Keep clustered-dot halftone and Bayer as compile-time options
Image adjustments:
- Add brightness, contrast, and gamma adjustments for better visibility
- Adjust RGB to grayscale conversion (25-50-25) to reduce blue darkness
Other changes:
- Fix MCU block indexing bug for correct picojpeg buffer access
- Pre-generate cover BMP when EPUB is loaded for faster sleep screen
## Summary
* Give activities name and log when entering and exiting them
* Clearer logs when attempting to debug, knowing where users are coming
from/going to helps
## Summary
* Unset openEpubPath on boot and set once epub fully loaded
## Additional Context
* If an epub was crashing when loading, it was possible to get the
device stuck into a loop. There was no way to get back to the home
screen as we'd always load you back into old epub
* Break this loop by clearing the stored value when we boot, still
jumping to the last open epub, but only resetting that value once the
epub has been fully loaded
## Summary
* This PR drastically reshapes the structure of the codebase, moving
from the concept of "Screens" to "Activities", restructing the files and
setting up the concept of subactivities.
* This should help with keep the main file clean and containing all
functional logic in the relevant activity.
* CrossPointState is now also a global singleton which should help with
accessing it from within activities.
## Additional Context
* This is probably going to be a bit disruptive for people with open
PRs, sorry 😞
