Revamp ThinkingSteps doc page: add Minimal, With Images, streaming text demos

- Reorganize examples into 6 sections: Basic, Minimal, Streaming, Streaming Text, With Images, Full Example
- Add Minimal demo (2 dots, simplest usage)
- Add With Images demo (ThinkingStepImage with captions)
- Add Streaming Text demo with character-by-character LLM-style output
- Enhance Full Example with ThinkingStepImage for complete sub-component coverage
- Remove redundant Dot Mode section
- Unify label/description font size to 13px with color contrast differentiation
- Install measurer package

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>