Consolidate documentation into unified getting started guide

This commit merges SYNDROME_DATASET.md and PIPELINE_ILLUSTRATION.md into
a single comprehensive GETTING_STARTED.md guide in the examples folder.

Changes:
- Create examples/GETTING_STARTED.md with unified content
- Add UAI format introduction for beginners
- Update all file paths to reflect new dataset organization
- Remove redundant datasets/SYNDROME_DATASET.md
- Remove redundant examples/PIPELINE_ILLUSTRATION.md

The new guide provides:
- Quick start instructions
- Step-by-step pipeline explanation
- Detailed format documentation (.stim, .dem, .uai, .npz)
- Code examples for all use cases
- Troubleshooting and best practices

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: ChanceSiyuan