Pre-release archive, code frozen for open source preparation

docs: update documentation for SDK v1.7.0 release

- Update main README with v1.7.0 features and examples
- Add SDK architecture diagram to architecture.md
- Update roadmap with completed v1.7.0 features
- Update components.md with correct SDK package info
- Highlight new features: file upload, offline mode, E2E encryption,
  webhook handlers, storage adapters, multi-tab coordination

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Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>