`coder whoami` and `coder list` can surface low-level JSON decode errors
when a reverse proxy, SSO portal, or incorrect Coder URL returns HTML
with a successful HTTP status.
Add a shared SDK JSON response decoder and use it for the user and
workspace list endpoints so these commands return a structured,
actionable API response error instead. Refs #27044
Reviewed and updated by Coder Agents on behalf of @dylanhuff-at-coder.
* feat: added whomai cmd to coder cli
* refactor: update Coder CLI's whoami command to use client URL instead of deployment config
* feat(cli): add unit tests for the whoami command
* chore(docs): add coder command to fetch authenticated user info
* chore(doc): update help desc
dylanhuff-at-coder