milestones create fails with `$projectId` of required type `String!` was not provided

[iamfj]

Description

The milestones create command fails when attempting to create a project milestone. The GraphQL variables are not being passed correctly to the mutation.

Steps to Reproduce

linearis milestones create "My Milestone" --project "My Project"

Expected Behavior

A new milestone is created under the specified project.

Actual Behavior

{
  "error": "GraphQL request failed: Variable \"$projectId\" of required type \"String!\" was not provided."
}

Root Cause

In the milestone service, the GraphQL variables are passed as a nested { input } object, but the CreateProjectMilestone mutation expects $projectId, $name, $description, and $targetDate as individual top-level variables.

The service wraps them in { input: { projectId, name, ... } } instead of passing { projectId, name, ... } directly.

Environment

• Branch: next (PR feat!: complete architecture redesign with GraphQL codegen, auth system, and developer tooling #45)
• Affects: milestones create command