## Summary
Simplify duplicated code in `XtcReaderActivity` to use
`ReaderUtils::detectPageTurn`. This implementation is now shared with
`EpubReaderActivity` and `TxtReaderActivity`. Also deduplicated the
chapter skip time constant.
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### AI Usage
While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.
Did you use AI tools to help write this code? _**PARTIALLY**_
## Summary
Extract shared reader utilities (`ReaderUtils.h`) to reduce duplication
across `EpubReaderActivity`, `TxtReaderActivity`, and (upcoming)
`MarkdownReaderActivity`.
Utilities extracted:
- `applyOrientation()` — orientation switch logic
- `detectPageTurn()` — page navigation input detection
- `renderAntiAliased()` — grayscale anti-aliasing pass
- `displayWithRefreshCycle()` — refresh mode cadence
- `GO_HOME_MS` — back button timing constant
## Impact
Flash: 32 bytes saved (6006441 → 6006409 bytes). Minimal immediate gain,
but meaningful once markdown reader and future reader types share these
functions.
Code quality: Eliminates ~100 lines of duplicated logic spread across
multiple files. All readers now follow the same patterns for
orientation, input handling, and rendering.
## Rationale
This refactor is preparation for markdown support, which requires
identical input and rendering logic. Instead of copy-pasting these
patterns a third time, all readers now share a single, tested
implementation. Future reader types can reuse `ReaderUtils` without
duplication.
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## AI Usage
Did you use AI tools to help write this code? YES Claude extracted the
code, under my guidance. Tested on my device and seems to work fine.
