Migrate current editor into apps/motion-toolkit

[iocfinc]

Problem or opportunity

The existing motion editor needs to live under a dedicated toolkit app boundary so the repository can evolve into a suite without breaking current behavior.

Proposed change

Move the current editor into apps/motion-toolkit, update routing and imports, and keep the existing motion workflow stable while the suite shell is introduced.

Success criteria

• Motion Toolkit has a dedicated app entry point
• Existing motion editor behavior remains functionally intact
• Legacy entry points redirect cleanly to the toolkit route where needed

Constraints or scope notes

• Epic: Epic: Suite foundation: repo restructure into apps and shared packages #14
• Avoid unnecessary behavior changes while moving the editor

[github-actions]

Issue intake checklist:

• Run agent/skills/read_issue.md.
• Classify the issue as Feature, Bug, Documentation, or Refactor.
• Record priority and affected components.
• Keep the lead agent focused on orchestration and choose bounded sub-agents from skills.md for non-trivial work.
• Route feature work to agent/skills/plan_feature.md.
• Route bug work to agent/skills/triage_bug.md.
• For frontend-facing work, plan browser debugging and screenshot validation before PR prep.