Bone Flow Editor v1.0.35 - Realtime Preview #001 Multi Sample Entry Audit

Scope
- Base: BoneFlow_Editor v1.0.34 Candidate
- Package Version: 1.0.35
- Realtime Preview Runtime remains #001 v1.0.6.

Changes
1. Status bar / command `boneflow.openRealtimeSample001` opens `/boneflow/sample/001/multi-instance-test.html`.
2. The verified three-instance sample remains unchanged in flow definitions: A Preview-only, B Preview-only, C Editor + Preview.
3. Added visible `HTML Download` control to the multi-instance sample. It downloads the same sample HTML as `index.html`.

Non-changes
- boneflow-realtime.js unchanged from v1.0.34.
- boneflow-realtime.css unchanged from v1.0.34.
- #002 Markdown sample files unchanged from v1.0.34.
- Flow Editor runtime files unchanged from v1.0.34.
