Improve workflow discovery with inferred frontend-to-backend route links

[AshwaniKharwar]

Summary

Improve architecture-graph workflow discovery by inferring frontend-to-backend route connections and using them to surface more meaningful visualizer flows.

Included work

• Add evidence-backed LLM inference for frontend-to-backend route links during graph initialization.
• Expand workflow discovery and prioritize frontend components that reach API routes as visualizer flow roots.
• Detect generic fetch-wrapper calls so client-to-route relationships are retained.
• Improve enrichment intent quality and source ranges used by graph/query output.
• Preserve the completed retrieval improvements from issues Increase default AI-agent retrieval top-k from 5 to 10 #4 and Include source line numbers in query result locations #5: default top-10 results and source line numbers.

Validation

The feature branch includes focused coverage for route inference, extractors, flow discovery, visualizer behavior, persistence, agent-loop behavior, and embeddings.