* **New Features**
* Time and delay utilities added (ticks, ms, µs); SD card now uses an expansion-header CS pin; HTTP downloads warn when run on the GUI task and yield to avoid blocking.
* **Bug Fixes / Reliability**
* Many hard-crash paths converted to guarded checks to reduce abrupt termination and improve stability.
* **Tests**
* Unit tests added to validate time and delay accuracy.
* **Chores**
* License header and build/macro updates.
## App state
Improved app state management in `LoaderService` and `GuiService`:
- Re-ordered some of the state transitions
- Hardened `GuiService` for repeated events (that might trigger a re-render of an app that's already rendered)
- Validate state transitions in `LoaderService` and crash if an app transitions from the wrong state to the next one.
## LoaderService
- Removed `tt::loader::` functions and expose `LoaderService` interface publicly.
- Implement `stopAll()` and `stopAll(id)` which stops all instances of an app, including any apps that were launched by it.
- Rename `stop()` functions to `stopTop()`
- Created `stopTop(id)` which only stops the top-most app when the app id matches.
- Moved `loader::LoaderEvent` to `loader::LoaderService::Event`
- Changed app instance `std::stack` to `std::vector`
## Improvements
- `ElfApp`: error 22 now shows a hint that `main()` might be missing
- Starting, installing and uninstalling apps now stops any running app (and its children) on the stack
## Bugfixes
- `HttpdReq` out of memory issue now shows an error message and doesn't crash anymore (this would happen on devices without PSRAM with WiFi active, when an app was installed)
- `GuiService::hideApp()` lock should not wait for timeout and now waits indefinitely
- `Buildscript/release-sdk-current.sh` deletes the previous local release before building a new one
## Code correctness
- App classes were made `final`
- Apps that had a `void start()` now have a `LaunchId start()`
- `tt::app::State`: renamed `Started` to `Created` and `Stopped` to `Destroyed` to properly reflect earlier name changes
- Refactor `AppManifest`: add new fields and rename existing ones
- Parse and validate the manifest from an app that is being installed.
- Remove deprecated `scoped()` from `Lock`
- Create `Tactility/Paths.h`
- App loading at boot now properly parses the manifest files of external apps
- Properly lock both source and destination locations during app install
- Remove LVGL path variants from `AppPaths` and `ServicePaths`
- Removed `xPath` base classes for apps and services. There's now `AppPaths` and `ServicePaths`.
- Renamed app and service paths: "data" and "system" paths are now "user data" and "assets"
- Update ILI9341 driver to v2.0.1
- Lots of code cleanup for apps
- Refactor app "type" into "category" and added flags to the manifest (for show/hide statusbar and for hidden apps)
- Rename some ElfApp-related functionality and improved the way the static data was managed
- Rename "filebrowser" to "files"
- Added cstring functions to tt_init.cpp
- Minor fix in Boot app
- Updated external apps for SDK changes
Ken Van Hoeylandt