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.

ui/src/lib/wire.ts

@@ -117,6 +117,8 @@ export interface WireEdge {
   via?: string;
   registeredAt?: string;
   valueRef?: boolean;
+  /** Branch conditions the call site runs under — `!isUploading && isCollected`. */
+  when?: string;
 }
 
 /** Every edge between the focal symbol and ONE other symbol, as a single row. */
@@ -642,6 +644,56 @@ export interface WireMapPayload {
   timing: { elapsedMs: number; cached: boolean };
 }
 
+/* ---------------------------------------------------------------- screens -- */
+
+export interface WireScreen {
+  id: string;
+  path: string;
+  file: string;
+  line: number;
+  component: WireNodeRef | null;
+  incoming: number;
+  outgoing: number;
+}
+
+export interface WireScreenOrigin {
+  id: string;
+  node: WireNodeRef;
+  outgoing: number;
+  /** Shared chrome: how many screens render it. */
+  sharedBy?: number;
+}
+
+export interface WireScreenSite {
+  file: string;
+  line: number;
+  href: string;
+  method: string;
+  when: string;
+}
+
+export interface WireScreenLink {
+  id: string;
+  from: string;
+  to: string;
+  fromOrigin: boolean;
+  via: WireNodeRef[];
+  when: string;
+  sites: WireScreenSite[];
+  synthesized: boolean;
+}
+
+export interface WireScreensPayload {
+  routed: boolean;
+  entry: string | null;
+  screens: WireScreen[];
+  origins: WireScreenOrigin[];
+  links: WireScreenLink[];
+  dropped: number;
+  index: { lastIndexedAt: number | null; edges: number; files: number };
+  timing: { elapsedMs: number };
+}
+
 /* -------------------------------------------------------------- dead code -- */
 
 /** One symbol nothing in the index reaches. */