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

- Introduces trigger metadata for steps and edges to capture what fires a site (JS prop, on* option, or callback) to improve cross-boundary flow analysis.
- Extends parsing/analysis to detect triggers in JSX attributes, on* bindings, and late-bound callbacks; adds utilities (calleeText, lastSegment) to extract trigger sources.
- Ships new trigger structures (WireStepTrigger, trigger on WireStepSite/WireStep) and propagates trigger through built steps; updates step labeling to reflect trigger information.
- Adds triggerWords helper and uses it to render human-readable trigger descriptions in Steps UI, including edge labels and per-site visuals.
- Updates UI (ScreensView, StepsView) to display FIRES FROM information, with styling tweaks to highlight triggers and related elements; enhances tooltips and inline text wrapping for readability.
- Extends tests to cover trigger detection and rendering across various binding patterns (prop, option, callback) and inline RN listeners.
- Updates design/docs and changelog to reflect Expo Router integration, per-site trigger metadata, and the new Steps surface.

CHANGELOG.md

@@ -14,7 +14,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### New Features
 
-- **A Steps tab in `codegraph ui` — what happens from here.** Pick a screen (or search any symbol and choose *What happens from here*) and the viewer draws everything it sets in motion as typed steps: the handlers wired to its taps and listeners, the calls that cross into native code, the native events that come back, the store actions it writes, and the calls that leave the app into the network, storage, the device or telemetry — one box per step, an arrow for every way one leads to the next, and on each arrow the condition under which it happens. The plumbing between two steps (hooks, helpers, the components in between) is folded into the arrow and listed in the side panel, exactly as the Screens tab folds a tap's chain into one transition — and every call the panel lists says what it passes, read from the source as written (`SecureStore.setItemAsync('userEmail', values.email)`, `axios.post('/auth/login', { email, password })`), so a step is not just *that* something was stored or sent but *what*. Any step is the next anchor, any link opens as a Flow strip, a cap the walk hit is announced on the step it hit it at, and the picture travels in the URL. React Native + Expo apps get the full picture today; any project gets handlers, stores and calls that leave the index.
+- **A Steps tab in `codegraph ui` — what happens from here.** Pick a screen (or search any symbol and choose *What happens from here*) and the viewer draws everything it sets in motion as typed steps: the handlers wired to its taps and listeners, the calls that cross into native code, the native events that come back, the store actions it writes, and the calls that leave the app into the network, storage, the device or telemetry — one box per step, an arrow for every way one leads to the next, and on each arrow the condition under which it happens. The plumbing between two steps (hooks, helpers, the components in between) is folded into the arrow and listed in the side panel, exactly as the Screens tab folds a tap's chain into one transition — and every call the panel lists says what it passes, read from the source as written (`SecureStore.setItemAsync('userEmail', values.email)`, `axios.post('/auth/login', { email, password })`), so a step is not just *that* something was stored or sent but *what*. And each handler says what fires it — the JSX prop and its element (`onPress · <Button>`), the option it is written under (`onSubmit · useFormik(…)`), the listener or effect it runs from — read from the source at the call site, so `onPress={() => handleLogin(values)}` and Formik's `onSubmit` make `handleLogin` a step of its own with the event on the arrow into it. Any step is the next anchor, any link opens as a Flow strip, a cap the walk hit is announced on the step it hit it at, and the picture travels in the URL. React Native + Expo apps get the full picture today; any project gets handlers, stores and calls that leave the index.
 
 - **React Native apps: Swift native modules and their events connect end to end.** A JS call like `captureView.finalizeCaptureSession()` — where `captureView` is bound to `NativeModules.CaptureView` and the module is a Swift class exposed through an `RCT_EXTERN_MODULE` shim — now resolves to the Swift method itself instead of stopping at the constant, so `codegraph_explore`, the Flow strip and the Steps view follow the code into native. Native → JS events now also land on listeners written inline (`addListener('onZipComplete', (data) => { … })`), attributed to the component that registers them. Re-index after upgrading to pick the new edges up.