feat(smoke-matrix): boot config-only expo-router examples (with-router)

expo/examples ships with-router as a config-only template: package.json + app.json + README, with main set to expo-router/entry but no routes yet (npx create-expo-app -e with-router generates them at scaffold time). The matrix harness saw no App/index entry and skipped. Now: when an example has no entry but its package.json declares main as expo-router/entry, synthesize a minimal app/ tree (Slot + index route) under .smoke-entries/<name>-stub-app/ and route the wrapper through it. The expo-router-entry shims placeholder still does the actual mounting — what we gain is one more PASS row in the matrix proving the expo-router boot path.

Author: OmgImAlexis

scripts/ci/smoke-all-examples.sh

@@ -108,6 +108,7 @@ for dir in "${EXAMPLES_DIR}"/*/; do
   #             router scans the app/ dir.
   entry=""
   router=0
+  router_root=""
   for cand in App.tsx App.js index.tsx index.js; do
     if [[ -f "${dir}${cand}" ]]; then
       entry="${dir}${cand}"
@@ -118,6 +119,7 @@ for dir in "${EXAMPLES_DIR}"/*/; do
     router=1
     entry="${dir}app/_layout.tsx"
     [[ -f "${entry}" ]] || entry="${dir}app/_layout.js"
+    router_root="${dir}app"
   fi
   # Newer expo-router apps use a `src/app/` layout (with-graphql,
   # with-html, with-react-flow, with-tailwindcss, …). package.json
@@ -127,6 +129,38 @@ for dir in "${EXAMPLES_DIR}"/*/; do
     router=1
     entry="${dir}src/app/_layout.tsx"
     [[ -f "${entry}" ]] || entry="${dir}src/app/_layout.js"
+    router_root="${dir}src/app"
+  fi
+  # Config-only example: package.json points at expo-router/entry but
+  # the README leaves the routes for `npx create-expo-app -e <name>` to
+  # generate. `with-router` is the canonical one. Synthesize a minimal
+  # app/ dir next to the wrapper so the router has something to mount —
+  # this proves expo-router + its shim boot without touching the
+  # external submodule.
+  if [[ -z "${entry}" && -f "${dir}package.json" ]]; then
+    if grep -qE '"main"\s*:\s*"expo-router/entry"' "${dir}package.json"; then
+      stub_app="${WRAPPER_DIR}/${name//\//-}-stub-app"
+      mkdir -p "${stub_app}"
+      cat > "${stub_app}/_layout.tsx" <<'EOF'
+import {Slot} from 'expo-router';
+export default function Layout() {
+  return <Slot />;
+}
+EOF
+      cat > "${stub_app}/index.tsx" <<EOF
+import {Text, View} from 'react-native';
+export default function Index() {
+  return (
+    <View style={{flex: 1, alignItems: 'center', justifyContent: 'center', backgroundColor: '#0c0a09'}}>
+      <Text style={{color: '#fafaf9', fontSize: 18}}>${name} stub route</Text>
+    </View>
+  );
+}
+EOF
+      router=1
+      entry="${stub_app}/_layout.tsx"
+      router_root="${stub_app}"
+    fi
   fi
   if [[ -z "${entry}" ]]; then
     printf '%-40s  %-12s  %s\n' "${name}" 'SKIPPED' 'no App / index / app entry' >> "${SUMMARY}"
@@ -146,12 +180,10 @@ for dir in "${EXAMPLES_DIR}"/*/; do
     # build-time string) for the routes tree. We set it to the
     # absolute path of the example's app/ dir so the router resolves
     # against the right routes even though our bundle entrypoint
-    # is in apps/playground/.smoke-entries/.
-    if [[ -d "${dir}app" ]]; then
-      app_dir_abs="$(cd "${dir}app" && pwd)"
-    else
-      app_dir_abs="$(cd "${dir}src/app" && pwd)"
-    fi
+    # is in apps/playground/.smoke-entries/. For config-only examples
+    # (e.g. with-router) the router_root points at the synthesized
+    # stub app dir under WRAPPER_DIR.
+    app_dir_abs="$(cd "${router_root}" && pwd)"
     cat > "${wrapper}" <<EOF
 // Auto-generated by scripts/ci/smoke-all-examples.sh — do not edit.
 // expo-router smoke for ${name}.