docs: render hermes/connection-lifecycle diagrams as mermaid

[Ar9av]

Summary

• Replace the hand-drawn ASCII-art boxes in docs/hermes.md and docs/connecting-to-the-platform.md with real mermaid diagrams (sequenceDiagram + flowchart), matching the convention already used in docs/architecture.md / docs/canary.md.
• Renders as an actual SVG on the docs site (prismor-web already supports ```mermaid fences) instead of a dark, unreadable code block.

Test plan

• Verified mermaid syntax parses cleanly (no fallback/error state) for all 3 diagrams
• Confirmed on the local docs site that each renders as a proper SVG with correct multi-line labels