Add option to disable thinking animation shimmer effect + show token usage

The recent updates (around v1.0.73-v1.0.81) introduced enhanced spinner animations and visual effects to the thinking animation. While these improvements look polished, many users who love Claude Code specifically for its terminal minimalism find the shimmer and enhanced animations to be an unwelcome distraction. Also, would love the option to have the token spend/count back while thinking. This helps our team 1) get the visual output that the thinking is actually happening and 2) helps us track & understanding compute spend on the fly.

### Requested Feature
Add a configuration option to disable or revert the thinking animation effects back to the previous simple style.

Suggested Implementation:
```bash
claude config set thinking-animation simple # or "enhanced", "disabled"

Or as an environment variable:
CLAUDE_CODE_THINKING_ANIMATION=simple

Use Case

Users who chose Claude Code specifically for its clean, minimal terminal experience should have the option to
maintain that aesthetic without the newer visual effects.

Related

This relates to the "Enhanced spinner animations and status line visual hierarchy" improvements mentioned in
v1.0.73 release notes.

Version: v1.0.81 (current latest)

Much cleaner focus on the core issue - that the enhanced animations go against the minimalist terminal aesthetic
that draws people to Claude Code in the first place.