fix: auto-convert project name in settings form

[elias-ba]

Description

This PR fixes the project settings form to auto-convert project names to url-safe format (lowercase, hyphens, digits), matching the behavior of the project creation form.

Previously, entering a name like "DEP-burundi-datafi" in settings would fail validation since the form submitted the raw input directly. The creation form already handled this by converting via Helpers.url_safe_name/1, but the settings form did not.

Closes #4437

Validation steps

1. Go to a project's settings page
2. Edit the project name with uppercase letters or spaces (e.g., "DEP-burundi-datafi")
3. Verify the preview badge shows the converted name ("dep-burundi-datafi")
4. Save and confirm the project is renamed successfully

Additional notes for the reviewer

1. The raw_name field is not a virtual schema field — it's just a form input key that gets intercepted and converted before reaching the changeset (same pattern as the creation modal)
2. Removed the "invalid format" test for name since uppercase input is now auto-converted rather than rejected

AI Usage

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  with Claude Code)
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  (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

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.38%. Comparing base (32f1001) to head (653535d).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4436      +/-   ##
==========================================
+ Coverage   89.33%   89.38%   +0.05%     
==========================================
  Files         425      425              
  Lines       20133    20137       +4     
==========================================
+ Hits        17985    17999      +14     
+ Misses       2148     2138      -10     

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