Add per-step snapshots and PartOfPlan relation for motion plans

[Marcus (sucrammal)]

With frame descriptors in place, the replayer needs a renderable snapshot per trajectory step and a way to group a plan's spawned entities for teardown. Adds parsedPlanToSnapshots (ParsedPlan â Snapshot[]) and the PartOfPlan ECS relation (autoDestroy: 'source') so destroying a plan entity cascades to its members.

Changes

• Frontend: Adds plan-to-snapshots.ts building one Snapshot of proto Transforms per step, and relations.ts defining PartOfPlan
• Tests: Adds plan-to-snapshots.spec.ts (one snapshot per step, per-frame transforms, jointed pose baking) and relations.spec.ts (cascade destroy)

Stack

• PR Add motion plan JSON parser (parsePlan) #838
• PR Add frame-descriptor derivation for motion plans #839
• PR Add per-step snapshots and PartOfPlan relation for motion plans #840
• PR Add Motion Plan Replayer plugin shell (panel + upload + extraSource) #841
• PR ScrubbingUI to visualize parsed motion plan JSON #842
• PR Persist per-frame display config + fix axes-helper toggle #843

Links

• APP-9316

Testing

• Run npx vitest run src/lib/plugins/MotionPlanReplayer/tests/plan-to-snapshots.spec.ts â¦/relations.spec.ts
• Confirm N trajectory steps produce N snapshots and destroying the plan root removes all PartOfPlan members

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