fix(generator): use dynamic root type names in SelectionSets.ts

[jasonkuhrt]

Fixes #1353

Summary

Fix custom root type names in SelectionSets generator by using dynamic type references instead of hardcoded "Query" and "Mutation".

Problem

When using GraphQL schemas with custom root type names (e.g., QueryRoot instead of Query), the SelectionSets generator was hardcoding Query and Mutation type names in the $Document interface, causing TypeScript compilation errors.

Example problematic schema:

schema {
  query: QueryRoot
  mutation: MutationRoot  
}

type QueryRoot { getString: String }
type MutationRoot { setString(value: String\!): String }

Root Cause

In src/generator/generators/SelectionSets.ts lines 49-50:

// Before (hardcoded type names)
query?: Record<string, Query<${i._$Scalars}>>
mutation?: Record<string, Mutation<${i._$Scalars}>>

Solution

Replace hardcoded type names with dynamic references to actual root type names:

// After (dynamic type names)  
query?: Record<string, ${renderName(config.schema.kindMap.index.Root.query)}<${i._$Scalars}>>
mutation?: Record<string, ${renderName(config.schema.kindMap.index.Root.mutation)}<${i._$Scalars}>>