LTIUpdateandotherfixes (#418)

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## Summary by CodeRabbit

* **Documentation**
* Split LTI 1.3 integration into Brightspace/D2L, Canvas, and Blackboard
guides; updated flows and visuals.
* Streamlined Canvas setup into modular steps with code-tab examples and
images.
  * Reformatted LTI images and alignment across guides.
* Instructor updates: Actions moved to Progress tab; Grading tab renamed
to Basic Settings.
* Student dashboard moved to top navigation with new menu items and
Leaderboard; dashboard image updated.
* Added Assessment Auto-Generation section and updated tutorial video
embed.
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Author: LolaValente