Add QR pairing (terminal QR, in-app scanner, iris://pair deep link)

app/androidApp/src/main/AndroidManifest.xml

@@ -8,6 +8,9 @@
     <!-- M5: ntfy listener foreground service (dataSync type on API 34). -->
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE_DATA_SYNC" />
+    <!-- QR pairing (docs/20): the in-app scanner reads the camera. -->
+    <uses-permission android:name="android.permission.CAMERA" />
+    <uses-feature android:name="android.hardware.camera" android:required="false" />
 
     <application
         android:label="Iris"
@@ -38,8 +41,22 @@
                 <category android:name="android.intent.category.BROWSABLE" />
                 <data android:scheme="iris" android:host="chat" />
             </intent-filter>
+            <!-- QR pairing (docs/20): iris://pair deep link (scanned QR / link). -->
+            <intent-filter>
+                <action android:name="android.intent.action.VIEW" />
+                <category android:name="android.intent.category.DEFAULT" />
+                <category android:name="android.intent.category.BROWSABLE" />
+                <data android:scheme="iris" android:host="pair" />
+            </intent-filter>
         </activity>
 
+        <!-- QR pairing (docs/20): full-screen scanner launched from the
+             Connect screen. Not exported; started only by our own app. -->
+        <activity
+            android:name="iris.platform.QrScanActivity"
+            android:exported="false"
+            android:screenOrientation="portrait" />
+
         <!-- M4: serve cached media/documents to other apps (ACTION_VIEW). -->
         <provider
             android:name="androidx.core.content.FileProvider"

app/androidApp/src/main/kotlin/dev/iris/app/MainActivity.kt

@@ -16,11 +16,16 @@ import iris.platform.AndroidEnv
 import iris.platform.AndroidSecureStore
 import iris.platform.AppBridge
 import iris.platform.syncNtfyListener
+import iris.util.PairLink
 
 class MainActivity : ComponentActivity() {
     private val deepLinkChatId = mutableStateOf<String?>(null)
     private val deepLinkThreadId = mutableStateOf<String?>(null)
 
+    // QR pairing (docs/20): a parsed iris://pair link to prefill the Connect
+    // screen with.
+    private val pendingPair = mutableStateOf<PairLink?>(null)
+
     private val notificationPermission =
         registerForActivityResult(ActivityResultContracts.RequestPermission()) { /* result ignored */ }
 
@@ -37,7 +42,13 @@ class MainActivity : ComponentActivity() {
         setContent {
             val chatId by deepLinkChatId
             val threadId by deepLinkThreadId
-            IrisApp(store = store, deepLinkChatId = chatId, deepLinkThreadId = threadId)
+            val pair by pendingPair
+            IrisApp(
+                store = store,
+                deepLinkChatId = chatId,
+                deepLinkThreadId = threadId,
+                deepLinkPair = pair,
+            )
         }
     }
 
@@ -64,6 +75,14 @@ class MainActivity : ComponentActivity() {
      *  extras or an iris://chat/<id>?thread=<tid> URI). */
     private fun handleDeepLink(intent: Intent?) {
         val data = intent?.data
+        // QR pairing (docs/20): iris://pair?host=…&port=…&secure=…&token=… —
+        // the whole payload is in the query string; parse it with the shared
+        // PairLink parser.
+        if (data?.scheme == "iris" && data.host == "pair") {
+            val link = PairLink.parse(data.toString())
+            if (link != null) pendingPair.value = link
+            return
+        }
         val chatId =
             intent?.getStringExtra("chat_id")
                 ?: data?.pathSegments?.firstOrNull()