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.

__tests__/ui-steps-model.test.ts

@@ -70,7 +70,7 @@ describe('steps model', () => {
     const edges = [...model.edges.values()];
     expect(edges).toHaveLength(6);
     const toBridge = edges.find((e) => e.to === bridge.id)!;
-    expect(toBridge.label).toBe('!busy');
+    expect(toBridge.label).toBe('NOT busy');
     expect(toBridge.kind).toBe('bridge');
     const toEvent = edges.find((e) => e.to === event.id)!;
     expect(toEvent.synthesized).toBe(true);