[docs: autonomous-visual-synthesis] Add structural visuals to workflows

[beginwebdev2002]

Added Mermaid graphs to represent workflows in docs/ai-agent-orchestration.md, docs/vibe-coding-zero-approval-workflows.md, and docs/vibe-coding-agents.md.

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PR created automatically by Jules for task 504392928670650191 started by @beginwebdev2002

[google-labs-jules]

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