feat: Remotion explainer video — proposed data flow (abstract, ~42s)

[William-Hill]

Build a ~42s silent Remotion explainer animating the proposed SIS → Preflight → PDP → AR → Dashboard pipeline by following one cohort retention number across 5 scenes.

Spec: docs/superpowers/specs/2026-04-30-remotion-data-flow-explainer-design.md
Plan: docs/superpowers/plans/2026-04-30-remotion-data-flow-explainer.md

Acceptance

• npm run dev in remotion-dataflow/ plays the full 42s end-to-end
• Three rendered variants from one codebase: hybrid, generic, bishop
• "62%" persists across all 5 scenes (no remount)
• Scene 2 flicker (62 → 58 → 64 → 62) renders within 1.5s
• Scene 5 breadcrumb shows full lineage chain
• Captions baked into frames

Status

Implementation complete on branch feature/remotion-data-flow-explainer. Canonical render: remotion-dataflow/renders/latest.mp4 (4.5 MB, 42.048s, hybrid branding).

Out of scope

Voiceover, audio, accessibility track, mockup-grade UI fidelity (those are the follow-up issue).