- added conversion of playlist to explan
- fixed processing bug

[SAF][API] Adapt endpoints
- new endpoint
- field length in cont short serializer

[USB] Proto map system
- hidden by default
- handles cmaps
- handles timed flags
- can interact with main playback
- optional visual effects on signs

* autosave session status in URL
* limiting number of deduced items in explan to 23

- migrated to Python 3.12
- migrated to Django 4.2.7

(references #157)

Backend tests back to 100%
Backend code coverage up to 64%

- fixed tests (back to 100% success)
- added field in Explan model for write access

- limit actions on dests and/or playback when in a room

- changed visibility of volume to be reachable even without focus

- [SAF][API] disabled auth precheck for explan by name fetching

- added status of SAF instance
- fixed display of explorer action in destinations when not auth
- removed advanced playback tool until fixed

- [SAF] added endpoint for limited journal fetching
- [SAF] fixed URL preprocessing regression
- [USB] Minor UI cleaning

- [SAF] follow up on USO saving bug
- [UFB] Less empty space in history list
- [UFB] Option to ignore youtube playlist next

- [SAF] fix USO creation and manager
- [UFB] view and use exploration history for dest import

- [SAF] continue investigation for USO failing flagging
- [SAF] message more verbose when explan failing to set
- [UFB] fix of explan pick reset when refreshed

- fix explan test (100% tests OK)
- debug entry db bug

- randomize next destinations
- autoplay playlist when focus empty