remove pterm dependency, replace with printing to stdout

The server tui functionality doesn't seem too widely used and its usefulness is limited. The pterm module has frequent updates and pulls in a few dependencies that could be left behind.

My thought is to rip pterm out and have `otel-cli server tui` instead print spans to the terminal, with more detail than the current text UI can show.

The result should work in more terminals, with less fuss, while showing more details.

Start at the implementation of `otel-cli server tui` and inspect how the current terminal UI uses pterm and how spans are rendered. Define the stdout output and detail level from the issue, then verify that the command works across terminals and no longer requires pterm.

Written by the indexing model from the issue text.