marketing: align Killer Demo with no-progress positioning

[SignalLayerLabs]

Summary

Aligns the canonical MARGINAL Killer Demo with the new public positioning already shipped in #29.

AI agents repeat work that changed nothing. MARGINAL catches it.

Changes

• redesigns /demo/ around the no-progress loop
• adds Same action / Same state / No new evidence visualization
• separates Shadow Mode from Earned Enforcement
• keeps deterministic allocation results clearly separated from runtime-governance illustration
• preserves reproducibility and existing result semantics
• regenerates the Codex runtime and provenance

Claim discipline

The deterministic demo remains explicitly:

• not provider telemetry
• not a production benchmark
• not evidence that every agent workload saves compute