fix: install OTA updates through PackageInstaller

The refresh button found 2.2.3, downloaded it, and reported
"Kurulum reddedildi (imza uyuşmuyor?)" for a build signed with exactly the same
platform certificate as the one already running. The signature was never the
problem.

install() shelled out to `pm install -r` with a path inside the app's private
cache. pm does not read the file — it hands the path to the package manager
service, which opens it from its own process and SELinux context, where that
directory is not readable. The install failed for a reason nobody could see:
install() returned a bare boolean, and UpdateHook mapped every false to the one
message it had. The pm output that would have named the real error was captured
into a StringBuilder and discarded.

A PackageInstaller session takes no path. We open the archive ourselves, as the
app, and stream it into the session, so no second process ever has to reach our
cache. Approach taken from merthankaraman/DriveHub_Dort, which hit the same wall
on the same head unit.

Consequences worth knowing when reading a future failure:

- Committing a session is asynchronous, so the refresh button can only say an
  install started. OtaInstallResultReceiver has the verdict, and surfaces the
  package manager's own INSTALL_FAILED_* text rather than guessing.
- STATUS_PENDING_USER_ACTION is not an error. The receiver launches the
  confirmation activity the platform supplies.
- The PendingIntent must be MUTABLE or it arrives with no status extras.

install() now returns an enum, so a certificate mismatch, an unparseable or
wrong-package archive, and a failed session each say what they are.

Also checks the archive's package name against ours, which was a genuine gap:
the platform key signs every app on this unit, so a certificate match alone
never meant the APK was this app.

The `pm install -r` exit-code test goes with the shell-out it covered. Nothing
in the session path is exercisable off-device.

REQUEST_INSTALL_PACKAGES and the receiver are declared in the unstable manifest
only — the stable channel has no updater at all, and its merged manifest was
checked to confirm it gains neither.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

app/src/unstable/AndroidManifest.xml

@@ -1,3 +1,21 @@
 <?xml version="1.0" encoding="utf-8"?>
+<!-- Unstable channel only. The stable build has no self-update path, so neither the install
+     permission nor the session result receiver belongs in the main manifest. -->
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
-    android:sharedUserId="android.uid.system" />
+    android:sharedUserId="android.uid.system">
+
+    <!-- Needed for the PackageInstaller session that replaced `pm install -r`. On this
+         platform-signed build the platform may install without asking; when it does ask,
+         this is what lets the confirmation be raised at all. -->
+    <uses-permission android:name="android.permission.REQUEST_INSTALL_PACKAGES" />
+
+    <application>
+        <receiver
+            android:name=".OtaInstallResultReceiver"
+            android:exported="false">
+            <intent-filter>
+                <action android:name="com.evsuite.abrp.OTA_INSTALL_RESULT" />
+            </intent-filter>
+        </receiver>
+    </application>
+</manifest>