feat(expo-router): add Expo Router support for Screens and navigations and introduce Steps API

- Adds Expo Router integration with a new Screens view and a Steps API to surface screens and their transitions.
- Extends codegraph extraction/resolution to handle namespace objects, React hook bindings for handlers, and Swift RN bridge evidence; introduces per-site guard arguments and trigger metadata, enabling richer flow analysis across JS ↔ native boundaries.
- Introduces UI and data-model changes to represent conditions as words (WHEN/AND/OR/NOT), display per-site call arguments, and show what fires a site (triggers). Adds new utilities (ui/conditions.ts) and updates ScreensView and StepsView to render scenarios with multiple sites and “ways” counts.
- Implements site readers for WHEN/ARGS/TRIGGER, and wiring to expose steps via API endpoints (including /api/steps); enhances tests to cover namespace resolution, useCallback-driven handlers, and inline RN event listeners.
- Updates styling and templates to reflect the new wording, scenario rows, and per-site details, including NOT instead of leading negation strings and multi-way links.
- Documents and reflects changes in changelog and design docs to describe Expo Router integration and the Steps surface.

ui/src/lib/wire.ts

@@ -669,6 +669,7 @@ export interface WireScreenSite {
   line: number;
   href: string;
   method: string;
+  /** The conditions THIS site runs under (the whole chain's plus its own); '' when unconditional. */
   when: string;
 }
 
@@ -705,6 +706,10 @@ export interface WireStepSite {
   line: number;
   /** `push /capture`, `calls`, `client.post` — what the site does, in a word or two. */
   text: string;
+  /** What the site passes, abbreviated (`'userEmail', values.email`); '' for none; absent when unreadable. */
+  args?: string;
+  /** The conditions THIS site runs under (the whole chain's); '' when unconditional. */
+  when: string;
 }
 
 export interface WireStep {