polyfill for spa added. works now on android

src/composables/useAndroidBackButton.ts

@@ -0,0 +1,60 @@
+import { onMounted, onUnmounted, ref } from 'vue'
+import { useRouter } from 'vue-router'
+import { platform } from '@tauri-apps/plugin-os'
+import { getCurrentWindow } from '@tauri-apps/api/window'
+
+/**
+ * Handles Android back button to navigate within the app instead of closing it
+ * Mimics browser behavior: navigate back if possible, close app if on first page
+ */
+export function useAndroidBackButton() {
+  const router = useRouter()
+  const historyStack = ref<string[]>([])
+  let unlisten: (() => void) | null = null
+
+  // Track navigation history manually
+  router.afterEach((to, from) => {
+    console.log('[AndroidBack] Navigation:', { to: to.path, from: from.path, stackSize: historyStack.value.length })
+
+    // If navigating forward (new page)
+    if (from.path && to.path !== from.path && !historyStack.value.includes(to.path)) {
+      historyStack.value.push(from.path)
+      console.log('[AndroidBack] Added to stack:', from.path, 'Stack:', historyStack.value)
+    }
+  })
+
+  onMounted(async () => {
+    const os = platform()
+
+    if (os === 'android') {
+      const appWindow = getCurrentWindow()
+
+      // Listen to close requested event (triggered by Android back button)
+      unlisten = await appWindow.onCloseRequested(async (event) => {
+        console.log('[AndroidBack] Back button pressed, stack size:', historyStack.value.length)
+
+        // Check if we have history
+        if (historyStack.value.length > 0) {
+          // Prevent window from closing
+          event.preventDefault()
+
+          // Remove current page from stack
+          historyStack.value.pop()
+          console.log('[AndroidBack] Going back, new stack size:', historyStack.value.length)
+
+          // Navigate back in router
+          router.back()
+        } else {
+          console.log('[AndroidBack] No history, allowing app to close')
+        }
+        // If no history, allow default behavior (app closes)
+      })
+    }
+  })
+
+  onUnmounted(() => {
+    if (unlisten) {
+      unlisten()
+    }
+  })
+}