v1.6: fix HIGH security vuln — remove plaintext cookie backup

- Remove KEY_COOKIES_BACKUP plaintext fallback from PreferencesManager
- getCookies() now fails closed (force re-login) if EncryptedSharedPreferences unavailable
- Set android:allowBackup="false" to prevent adb backup extraction of session data
- Add missing gradle-wrapper.jar to repo

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/build.gradle.kts

@@ -11,8 +11,8 @@ android {
         applicationId = "me.khodak.claudeusage"
         minSdk = 26
         targetSdk = 34
-        versionCode = 6
-        versionName = "1.5"
+        versionCode = 7
+        versionName = "1.6"
     }
 
     signingConfigs {

app/src/main/AndroidManifest.xml

@@ -5,7 +5,7 @@
     <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
 
     <application
-        android:allowBackup="true"
+        android:allowBackup="false"
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"
         android:roundIcon="@mipmap/ic_launcher_round"

app/src/main/java/me/khodak/claudeusage/data/PreferencesManager.kt

@@ -27,18 +27,13 @@ class PreferencesManager(context: Context) {
 
     fun saveCookies(cookies: String) {
         securePrefs.edit().putString(KEY_COOKIES, cookies).apply()
-        // Plaintext backup — survives EncryptedSharedPreferences key rotation on reinstall
-        prefs.edit().putString(KEY_COOKIES_BACKUP, cookies).apply()
     }
 
-    fun getCookies(): String? =
-        securePrefs.getString(KEY_COOKIES, null)
-            ?: prefs.getString(KEY_COOKIES_BACKUP, null)
+    fun getCookies(): String? = securePrefs.getString(KEY_COOKIES, null)
 
     fun clearSession() {
         securePrefs.edit().clear().apply()
-        prefs.edit().remove(KEY_ORG_ID).remove(KEY_SESSION_START)
-            .remove(KEY_COOKIES_BACKUP).apply()
+        prefs.edit().remove(KEY_ORG_ID).remove(KEY_SESSION_START).apply()
     }
 
     fun saveOrgId(id: String) = prefs.edit().putString(KEY_ORG_ID, id).apply()
@@ -84,7 +79,6 @@ class PreferencesManager(context: Context) {
 
     companion object {
         private const val KEY_COOKIES = "session_cookies"
-        private const val KEY_COOKIES_BACKUP = "session_cookies_backup"
         private const val KEY_ORG_ID = "org_id"
         private const val KEY_SESSION_START = "session_start"
         private const val KEY_USAGE_DATA = "usage_data"