chore(deps): Take Dependabot's NuGet updates, with two restore fixes

[mpaulosky]

Replaces #211, Dependabot's grouped update of 32 NuGet packages, which failed restore and so failed every build and test job. This branch starts from that PR's branch and adds two fixes:

• Microsoft.OpenApi 3.10.2 → 2.12.2. Microsoft.AspNetCore.OpenApi 10.0.12 requires Microsoft.OpenApi >= 2.12.0 && < 3.0.0 (NU1608). main had 2.7.5, so 2.12.2 is still an upgrade. dependabot.yml now skips major Microsoft.OpenApi updates until ASP.NET allows 3.x, so this bump won't come back every week.
• Microsoft.AspNetCore.Components.Web 10.0.8 → 10.0.12. Radzen.Blazor 11.4.1 needs >= 10.0.12 (NU1109, downgrade). This brings it in line with the other ASP.NET 10.0.12 packages in the update.

I opened it from a separate branch rather than pushing to Dependabot's: Dependabot stops managing a branch once someone else commits to it.

Validation: dotnet build (Release) succeeds, and the pre-push hook ran every test project with 0 failures.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.05%. Comparing base (e6f2f42) to head (e1c2e99).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #216   +/-   ##
=======================================
  Coverage   82.05%   82.05%           
=======================================
  Files         117      117           
  Lines        2709     2709           
  Branches      389      389           
=======================================
  Hits         2223     2223           
  Misses        405      405           
  Partials       81       81           

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