CLI passthrough (PTY) mode, standalone snippet output

[carli2]

CLI passthrough (PTY), standalone snippets, and pager safeguards

Summary

• Add command passthrough mode: run a command in a colored PTY and convert its output to HTML.
• Introduce --standalone (-S) to emit a minimal inline HTML snippet wrapped in <code>.
• Disable auto‑pagers in PTY by default (GIT_PAGER=cat, PAGER=cat) to prevent hangs; users can override.
• Refresh --help, README/docs, and man page; add targeted tests.

Why

Capturing realistic colorized output from CLIs (e.g., git) usually requires a TTY. This PR makes it easy to run such commands, capture their ANSI-colored output, and convert it to HTML
reliably—without getting stuck behind pagers.

What’s Changed

• PTY passthrough execution with argument parsing and TERM=xterm-256color.
• --standalone (-S): like --inline but wrapped in <code style='white-space: pre;'>…</code> for convenient embedding.
• Pager safeguards in PTY mode: set GIT_PAGER=cat and PAGER=cat by default to avoid hangs.
• Documentation updates and new tests covering passthrough and pager behavior.

Usage

• Run a command and convert its colored output:

  ansi2html git log -p > git-log.html
  

• Separate ansi2html options from the child command:

  ansi2html --inline -- git log -p > inline-git-log.html

• Produce a minimal embeddable snippet:

  echo $'\e[31mRED\e[0m' | ansi2html --standalone

  short form:

  echo $'\e[31mRED\e[0m' | ansi2html -S

Behavior Notes

• Argument parsing:
  • After --, all args belong to the child command.
  • Without --, the first non-option token starts the child command; all following tokens belong to it.
• PTY environment:
  • Sets TERM=xterm-256color.
  • Captures stdout and stderr together for conversion.
• Pagers:
  • In PTY mode, sets GIT_PAGER=cat and PAGER=cat by default.
  • Override explicitly if desired, e.g. GIT_PAGER="less -R".

Docs & Tests

• Updated: --help, README, dedicated CLI docs, and the man page.
• Tests added/updated to cover passthrough execution and pager disabling.

Backwards Compatibility

• Existing pipelines and options continue to work unchanged.
• Pager behavior only changes in PTY passthrough mode and can be overridden.

Commits

• baa58eb: cli: add --standalone (-S), disable pagers in PTY, refresh help/docs/man, add tests
• 3d9e750: add passthrough “wrapper” mode to execute commands in a colored, non‑paged TTY

Checklist

• PTY passthrough execution
• --standalone (-S) snippet output
• Pager safeguards with override
• Docs/help/man updated
• Tests added and passing