fix: trigger module constructors for library assemblies

[thomhurst]

Fixes #4583

Problem

[Before(TestSession)] hooks in library projects weren't executing. Library projects that reference TUnit.Core don't have source generation active, so they don't get generated ModuleInitializers to register their hooks.

Solution

Reference a public type from each loaded library assembly using typeof(), which triggers the assembly's module constructor to run and register hooks.

Changes

• InfrastructureGenerator.cs:
  • Extract first public type from each assembly at compile time
  • Generate _ = typeof(Fully.Qualified.TypeName); instead of Assembly.Load()
• AssemblyInfoModel.cs: Store fully qualified type names instead of assembly names

Why This Works

Referencing a type via typeof() causes:

1. The assembly containing that type to load
2. The assembly's module constructor to execute
3. Hooks to be registered automatically

This approach is cleaner than explicitly calling reflection-based hook discovery and avoids making internal APIs public.

Testing

Verified with the reproduction repository from #4583:

• Before fix: Hook never executed ("BeforeTestSession is not run!")
• After fix: Hook executes correctly (fails on Docker connection, proving hook runs)

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.