docs: regenerate infographic for v0.4.1

[azmym]

Summary

Regenerates the architecture infographic from scratch (fresh NotebookLM notebook, current v0.4.1 source material) and replaces the existing asset.

The previous infographic predated the v0.4.0/v0.4.1 changes. The new one reflects the current state:

• Three-layer architecture: Coordination (7 hooks) to Reasoning (5 subagents) to Execution (gemini-mcp server to Gemini, Imagen, Veo, Lyria via Google AI Studio).
• All 5 subagents: validator, challenger, researcher, summarizer, reviewer, with roles.
• 9 skills (2 routers + 7 capability) and 5 slash commands called out.
• The new "Fail-Loud" safety protocol (agents return unknown rather than fabricating when a Gemini tool is unavailable).

README already references assets/infographic.png, so no markup change is needed.