[workshop-diagrams] Add theme-aware explanatory diagram for cache-memory deduplication loop

[github-actions]

Summary

Adds a light/dark SVG diagram illustrating the cache-memory deduplication loop to workshop/20-persistent-memory.md.

What changed

• Workshop file: workshop/20-persistent-memory.md — inserted a <picture> block at the start of the "Why Memory Matters" section
• New SVG (light): workshop/images/20-cache-memory-loop-light.svg
• New SVG (dark): workshop/images/20-cache-memory-loop-dark.svg

New concept vs migration

This is a new concept diagram — the file had no existing images. The cache-memory run loop was explained only in prose.

Why it helps learners

The deduplication pattern (read → fetch → filter → report → write → repeat) is the core mental model of this step. A left-to-right numbered flow with a dashed feedback arrow makes the cross-run persistence concrete and immediately scannable. Without the diagram, learners must reconstruct the loop from two separate paragraphs and a code block.

Technical details

• Canvas: 1200×560 px, consistent with existing workshop SVG pairs
• Light palette: #f2f5f3 background, #08872b accent
• Dark palette: #101411 background, #5fed83 accent
• Primer semantic state color on the Open badge (#1a7f37 / #3fb950)
• data-visual-kind="diagram", data-visual-id, data-node on all nodes
• role="img" and aria-label on both SVG roots
• No gradients; no Unicode icon characters
• Both files pass scripts/check-svg-visual-language.js with zero violations
• Markdown linter: zero issues

Warning

Firewall blocked 1 domain

The following domain was blocked by the firewall during workflow execution:

• awmgmcpg

To allow these domains, add them to the network.allowed list in your workflow frontmatter:

network:
  allowed:
    - defaults
    - "awmgmcpg"

See Network Configuration for more information.

Generated by 🧠 Workshop Explanatory Diagram Generator · 111.5 AIC · ⌖ 7.74 AIC · ⊞ 6.8K · ◷

• expires on Aug 26, 2026, 5:06 AM UTC