v0.2.1

🔧 Fix: bundled CLI now resolves correctly after global install

npm install -g ./autosota-0.2.1.tgz is all you need on a clean machine.
In v0.2.0, the bundled model CLI was present on disk but unreachable from PATH
after a global install (npm only links the top-level package's bin entries, not
nested dependencies). v0.2.1 resolves the bundled binary at startup and prepends
it to the subprocess PATH automatically — no separate install step required.

New: autosota login

One-time interactive setup for accepting terms of service. Replaces the previous
workaround of invoking an external command directly. Full workflow now has a
single entry point: autosota.

Docs

• docs/walkthrough.md — step-by-step visual tutorial
  using SAVVY as the example paper, from install to optimization_curve.png.
• README updated: removed outdated install instructions; first-run setup is now autosota login.