Add skill: csthink/dashmotion

[csthink]

Adds csthink/dashmotion to Community Skills → Development and Testing (one line; no other entries touched).

dashmotion is a Claude skill that turns plain English or Mermaid source into dark-themed, animated technical diagrams as self-contained HTML/SVG — flowcharts whose connectors visibly flow, and architecture diagrams where requests travel as light dots through the system.

• Repo (MIT): https://github.com/csthink/dashmotion
• Live demo: https://csthink.github.io/dashmotion/

Why it meets the bar

• Proven, maintained skill — not a brand-new upload. Released through v2.0 → v2.2.4 with a published CHANGELOG, docs (docs/how-it-works.md), a committed eval harness, and a live demo.
• Validated: claude plugin validate --strict passes; standard skills/dashmotion/SKILL.md bundle that installs and loads cleanly.
• Zero data footprint: no hooks, no MCP servers, no network access, no telemetry — it only generates local HTML/SVG files.
• Follows the Quality Criteria: third-person description; progressive disclosure (mode references and templates loaded on demand, not inline); no absolute paths; no blanket tool grants.

CONTRIBUTING checklist: public repo with a working skill ✓ · documentation (README + SKILL.md + docs/) ✓ · author/org prefix ✓ · description ≤ 10 words ✓ · links verified ✓ · single line added ✓