docs: add project config & infrastructure

[frydj]

Summary

• CLAUDE.md: Project documentation for AI-assisted development, including tone guidelines, code standards, and verification instructions
• Sidebar restructure: Complete navigation reorganization with new sections for Getting Started, Learn (Foundations/Working with Data/Modeling/Security/Advanced), Reference (HTTP API/Querying/Transactions), and Examples (Domain/Feature Showcases)
• Config updates: Docusaurus theme configuration, package.json version bump, homepage link updates
• .tonal-references/: Preserved original tutorial as voice reference for documentation style
• .env.local.example: Environment variable template for Claude Code integration

This PR establishes the foundation for the documentation restructure. The sidebar references pages added in subsequent PRs in this stack.

Test plan

• bun run build passes (will fail until full stack merges due to sidebar refs)
• Review sidebar structure for logical organization

[frydj]

• docs: add feature showcase examples #71
• docs: add domain example datasets #70
• docs: add feature reference docs #69
• docs: reorganize cookbook #68
• docs: restructure querying reference #67
• docs: restructure HTTP API reference #66
• docs: add advanced topics #65
• docs: add security guides #64
• docs: add modeling guides #63
• docs: add working with data guides #62
• docs: reorganize learn foundations #61
• docs: add getting started guides #60
• docs: add project config & infrastructure #59 👈 (View in Graphite)
• main

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