Update gist output domain to gisthost

[simonw]

The --gist option should output a link to gisthost.github.io rather than gistpreview.github.io

The JavaScript logic injected into the pages should now work for both of those domains, so it should detect if the page is being served on gisthost.github.io OR gistpreview.github.io

• Update preview URLs to use gisthost.github.io instead of gistpreview.github.io
• Update JavaScript to detect both gisthost.github.io and gistpreview.github.io domains for backward compatibility with existing links
• Update help text and README to reference the new domain

https://gisthost.github.io/?e33364139d39625eda6fbbe8527f5902/index.html

[simonw]

It works:

uv run claude-code-transcripts web --gist

? Select a session to import: 2025-12-31T04:14:19  Update gist output domain to 
gisthost
Fetching session session_01VWHvYmmP6WBafz5wCEMCXF...
Generating HTML in /var/folders/x6/31xf1vxj0nn9mxqq8z0mmcfw0000gn/T/claude-session-session_01VWHvYmmP6WBafz5wCEMCXF/...
Auto-detected GitHub repo: simonw/claude-code-transcripts
Generated page-001.html
Generated /private/var/folders/x6/31xf1vxj0nn9mxqq8z0mmcfw0000gn/T/claude-session-session_01VWHvYmmP6WBafz5wCEMCXF/index.html (1 prompts, 1 pages)
Output: /private/var/folders/x6/31xf1vxj0nn9mxqq8z0mmcfw0000gn/T/claude-session-session_01VWHvYmmP6WBafz5wCEMCXF
Creating GitHub gist...
Gist: https://gist.github.com/simonw/e33364139d39625eda6fbbe8527f5902
Preview: https://gisthost.github.io/?e33364139d39625eda6fbbe8527f5902/index.html

https://gisthost.github.io/?e33364139d39625eda6fbbe8527f5902/index.html