hex-to-canvas: footer link to source thread + make canvas creation opt-in

[okoshy]

Summary

Two improvements to the hex-to-canvas skill:

1. Always link the source Hex thread — every canvas built from a Hex thread now ends with a footer linking back to the thread conversation it was generated from, keeping canvases auditable.
2. Make canvas creation opt-in — the skill now only triggers when the user explicitly asks for a canvas/dashboard. Using the Hex MCP or asking a data question no longer implies a canvas should be built.

Changes

• skills/hex-to-canvas/SKILL.md
  • Tightened the description frontmatter: "Use ONLY when the user explicitly asks to build a Cursor canvas or dashboard… Do NOT use for ordinary Hex data questions/KPI lookups."
  • Added a "When to use this skill" section with positive and negative examples, directing ordinary data questions to hex-business-analytics-question and saying to answer first / offer (not build) a canvas when unprompted.
  • Added workflow step 8 ("Link the source thread") and an "Always link the source Hex thread" section with concrete guidance (use the real url/appUrl, never guess; handle multiple threads; combine with project/dashboard links) plus a sample footer Card snippet.
  • Added footer-link entry to the component-mapping list and an "Always link the source thread" rule.
• README.md: Updated the hex-to-canvas description to note it is opt-in and adds a footer link back to the source Hex thread.

Notes

Documentation/instruction-only changes to the skill; no executable code to test.