tea --magic=install; tea --magic=uninstall

[mxcl]

I don't like the ergonomics of --magic=install but it was quick n’ easy. Will revise when I have better ideas

[what-the-diff]

PR Summary

• Upgradation of the CLI tool version
  The command-line interface tool 'tea' used for managing tasks has been updated, enhancing its capacities with the latest version (from 0.38.4 to 0.39.0).

• Incorporation of a new command
  A fresh instruction command tea node@16 --version has been introduced, which paves the way for checking the 'node' version easily.

• Improvement in readability
  Some linguistic improvements were made in the instruction manual (README.md). These changes are designed to enhance clarity and comprehensibility for users.

• Introduction of a new feature - 'magic'
  A new utility 'magic' has been introduced via app.magic.ts. It has the capability to make alterations (either installations or uninstallations) to shell rc files. This can be seen as a tool for managing shell rc files more efficiently.

• Usage of the new 'magic' feature
  The main application (app.main.ts) has been revised to utilize the 'magic' feature for install or uninstall modes. This allows users to efficiently manage their modes of usage for this tool.

[jhheider]

--add and --rm?

[jhheider]

Looks sane. Better for shell switchers.

[mxcl]

I considered a --magic that “magically” determines shell (by testing syntax or magic variables), but it's not worth it probs.

As it stands if you don't specify =shell we determine it by inspecting $SHELL however it turns out this may be wrong or unset. There's no POSIX standard for determining shell. You can try to inspect the process tree and (for sure) that's what ChatGPT wants us to do.

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This aside is somewhat irrelevant as this PR just adds magic to any files we can find that we support.