release: publish @ivanmkc/termchart-viewer or remove the broken npx fallback

[ivanmkc]

Problem

The CLI and documentation advertise termchart serve, whose fallback invokes npx @ivanmkc/termchart-viewer when the viewer is not available from the monorepo. As of 2026-08-29, npm view @ivanmkc/termchart-viewer version returns 404: the package is not published.

This means serving works from a repository checkout, but the published standalone CLI cannot self-install the viewer as its help text implies.

Decision required

Choose one supported distribution model:

1. Publish @ivanmkc/termchart-viewer and add a release path that keeps it compatible with the CLI, or
2. Bundle or otherwise locate the viewer with the CLI and remove the unpublished-package fallback and documentation.

Acceptance criteria

• A clean machine with only the published CLI can start the viewer using the documented command.
• CLI failure messaging describes the supported installation path.
• Release metadata/checks cover the chosen viewer distribution model.
• Local viewer + restricted ngrok instructions in ops: support local viewer hosting through a restricted ngrok tunnel #303 work from the supported artifact.