docs: replace basic example with comprehensive real-world examples

[brndnmtthws]

• Add complete workflow example showing workspace discovery, graph building, cycle detection, and report generation
• Include visualization example demonstrating Mermaid and DOT output generation
• Add filtering example for production-only dependency analysis
• Include targeted analysis example for finding cycles in specific workspaces
• Fix import paths for ConfigBuilder to use common module
• Use proper API patterns (graph_builder.graph() instead of returning graph)
• Add proper error handling with miette::IntoDiagnostic
• Make all examples use realistic monorepo scenarios