feat(expo-router): add Expo Router support for screens and navigates

Introduce Expo Router integration: a new framework resolver, route-based screen nodes, and navigates edges, plus a /api/screens endpoint and a Screens UI view. Adds branch-guard-driven labeling of edges, resolution logic, and tests to cover extraction, resolution, and end-to-end flow. This enables CodeGraph UI to surface screens and transitions from Expo Router apps.

src/types.ts

@@ -67,6 +67,7 @@ export const EDGE_KINDS = [
   'instantiates',    // Creates instance of class
   'overrides',       // Method overrides parent method
   'decorates',       // Decorator applied to symbol
+  'navigates',       // Navigates to a screen/route (Expo Router `router.push('/x')`)
 ] as const;
 
 export type EdgeKind = (typeof EDGE_KINDS)[number];