Refactor Projects Dashboard & Fix Last Activity Bug

[elias-ba]

Description

This PR refactors the projects dashboard page by encapsulating the three different components of the page into separate live components. This change makes the page more reusable, improves separation of concerns, and ensures the page itself doesn't handle state and events for these components. Additionally, this PR also fixes a bug identified in the last activity column of the projects list. The bug was due to the last activity column displaying the value of the updated_at column from the projects table. The query has been updated to fetch the most recent updated_at value of the workflows for each project.

Fixes #2593

Validation steps

1. Log in to the app.
2. Navigate to the projects dashboard page and confirm that both the welcome section and the projects table load correctly.
3. Expand/Collapse the welcome section to ensure it functions as expected.
4. Verify that clicking on the welcome cards loads the associated arcade videos properly.
5. Test that creating a new project successfully adds it to the projects list.
6. Confirm that the last activity column now correctly reflects the most recent updated_at date of the workflows for each project.

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Pre-submission checklist

• I have performed a self-review of my code.
• I have implemented and tested all related authorization policies. (e.g., :owner, :admin, :editor, :viewer)
• I have updated the changelog.
• I have ticked a box in "AI usage" in this PR

[codecov]

Codecov Report

Attention: Patch coverage is 97.22222% with 3 lines in your changes missing coverage. Please review.

Project coverage is 90.84%. Comparing base (94b7bfc) to head (e59f551).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ghtning_web/live/dashboard_live/welcome_section.ex	86.95%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2606      +/-   ##
==========================================
+ Coverage   90.79%   90.84%   +0.04%     
==========================================
  Files         318      320       +2     
  Lines       11178    11215      +37     
==========================================
+ Hits        10149    10188      +39     
+ Misses       1029     1027       -2     

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[jyeshe]

Great component building! 💯