Fix button rendering with Observable html template

[rdhyee]

Problem

Color-code button has rendering issues on production site:

• Button renders as black box (no visible text)
• Code block shows despite echo: false and echo: fenced directives
• Observable Inputs.button() widget doesn't render properly in Quarto

Solution

Replace Inputs.button() with Observable html template literal:

• Creates button using html template with inline styling
• Implements viewof + CustomEvent pattern for Observable reactivity
• Maintains compatibility with existing classification handler

Testing

✅ Tested locally with Playwright MCP:

• Button renders with proper blue styling
• Click event triggers classification handler
• Console shows "Classifying dots by type..."
• No black box or unwanted code visibility

Changes

• tutorials/parquet_cesium.qmd (lines 50-70): Button implementation
  • Replaced Inputs.button() with html template
  • Added viewof classifyTrigger with custom onclick
  • Aliased as classifyDots for handler compatibility

Deployment

Ready to merge and deploy to https://isamples.org/tutorials/parquet_cesium.html

🤖 Generated with Claude Code