feat(namespace): update fully qualified type references

[CalvinAllen]

Summary

• Add support for updating fully qualified type references like OldName.MyClass → NewName.MyClass
• Uses word boundary regex (\b) to avoid partial matches (e.g., SomeOldName won't become SomeNewName)
• Scans all .cs files across the entire solution

Changes

• Added UpdateFullyQualifiedReferencesInSolution and related methods to SourceFileService
• Added Step 11 to the rename process in RenamifyProjectCommand
• Updated progress dialog to show the new step

Examples handled

// Before
var service = new OldName.Services.MyService();
OldName.Helpers.Utility.DoSomething();
typeof(OldName.MyClass)

// After  
var service = new NewName.Services.MyService();
NewName.Helpers.Utility.DoSomething();
typeof(NewName.MyClass)

Test plan

• Rename a project that has fully qualified references in other projects
• Verify partial matches are NOT replaced (e.g., SomeOldName.Foo stays unchanged)
• Verify progress dialog shows 11 steps

Closes #36