feat: migrate mutationScope generation to generateQueries

[arlindaxhemailii]

Summary

Re-implements mutationScope support in the active TypeScript query generation flow (generateQueries.ts).

Background

The original mutationScope implementation was built on top of the Handlebars-based query generator that existed on main at the time. During the merge with the include-tags work, query generation had already been migrated to the TypeScript generator, so the restored Handlebars files were no longer part of the active generation path.

As a result, the mutationScope option was present but was not being applied by the current generator.

Changes

• Re-implement mutationScope generation in generateQueries.ts
• Remove legacy Handlebars generation files restored during the merge
• Fix mutationEffects + mutationScope interaction in mutation callbacks
• Verify generated mutation hooks correctly produce scoped mutations