Add setting toggle that allows status bar display options in EpubReader.
Supported options would be as follows:
- FULL: display as is today
- PROGRESS: display progress bar only
- BATTERY: display battery only
- NONE: hide status bar
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Co-authored-by: Dave Allie <dave@daveallie.com>
## Summary
* **What is the goal of this PR?**
Add a "Continue Reading" feature to improve user experience when
returning to a previously opened book.
* **What changes are included?**
- Add dynamic "Continue: <book name>" menu item in Home screen when a
book was previously opened
- File browser now starts from the folder of the last opened book
instead of always starting from root directory
- Menu dynamically shows 3 or 4 items based on reading history:
- Without history: `Browse`, `File transfer`, `Settings`
- With history: `Continue: <book>`, `Browse`, `File transfer`,
`Settings`
## Additional Context
* This feature leverages the existing `APP_STATE.openEpubPath` which
already persists the last opened book path
* The Continue Reading menu only appears if the book file still exists
on the SD card
* Book name in the menu is truncated to 25 characters with "..." suffix
if too long
* If the last book's folder was deleted, the file browser gracefully
falls back to root directory
* No new dependencies or significant memory overhead - reuses existing
state management
## Summary
* Use single unified cache file for book spine, table of contents, and
core metadata (title, author, cover image)
* Use new temp item store file in OPF parsing to store items to be
rescaned when parsing spine
* This avoids us holding these items in memory
* Use new toc.bin.tmp and spine.bin.tmp to build out partial toc / spine
data as part of parsing content.opf and the NCX file
* These files are re-read multiple times to ultimately build book.bin
## Additional Context
* Spec for file format included below as an image
* This should help with:
* #10
* #60
* #99
## 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
## Problem
Reading progress.bin used `SD.exists()` then `SD.open()` without
checking if open succeeded. Race conditions or SD errors could cause
file handle to be invalid.
## Fix
- Removed redundant `SD.exists()` check
- Check if file opened successfully before reading
- Verify correct number of bytes were read
## Testing
- Builds successfully with `pio run`
- Affects: `src/activities/reader/EpubReaderActivity.cpp`
## Problem
The status bar title truncation loop crashes when the chapter title is
shorter than 8 characters.
```cpp
// title.length() - 8 underflows when length < 8 (size_t is unsigned)
title = title.substr(0, title.length() - 8) + "...";
```
## Fix
Added a length guard to skip truncation for titles that are too short to
truncate safely.
## Testing
- Builds successfully with `pio run`
- Affects: `src/activities/reader/EpubReaderActivity.cpp`
## 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 😞
