fix(verify-flatpak): bundle gradle-9.5.1-all, rewrite wrapper URL

The Gradle wrapper inside the flatpak build was trying to download
gradle-9.5.1-all.zip from services.gradle.org and failing because the
build phase has no network. Two problems:

1. The bundled gradle distribution was gradle-9.4.1-bin.zip
   (mismatched version + bin instead of all).
2. The overlay was missing the sed step that rewrites
   distributionUrl in gradle-wrapper.properties to point at the
   bundled file.

Fix: bump bundled distribution to gradle-9.5.1-all.zip (matches
gradle/wrapper/gradle-wrapper.properties exactly) and add the
distributionUrl sed before any gradlew invocation. Hash pulled from
the official services.gradle.org/.../*.sha256 endpoint.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

scripts/verify-flatpak/desktop-offline.yaml

@@ -68,6 +68,8 @@ modules:
       - install -Dm644 -t /app/share/icons/hicolor/scalable/apps org.meshtastic.desktop.svg
       - install -Dm644 -t /app/share/applications org.meshtastic.desktop.desktop
       - install -Dm644 -t /app/share/metainfo org.meshtastic.desktop.metainfo.xml
+      # Redirect the Gradle wrapper to the bundled distribution (no network).
+      - sed -i 's|distributionUrl=.*|distributionUrl=gradle-all.zip|' gradle/wrapper/gradle-wrapper.properties
       - echo "org.gradle.java.installations.auto-detect=false" >> gradle.properties
       - echo "org.gradle.java.installations.auto-download=false" >> gradle.properties
       - echo "org.gradle.java.installations.paths=/usr/lib/sdk/openjdk21/jvm/openjdk-21,/usr/lib/sdk/openjdk17/jvm/openjdk-17" >> gradle.properties
@@ -90,8 +92,10 @@ modules:
       - type: dir
         path: meshtastic-android
       - type: file
-        url: https://services.gradle.org/distributions/gradle-9.4.1-bin.zip
-        sha256: 2ab2958f2a1e51120c326cad6f385153bb11ee93b3c216c5fccebfdfbb7ec6cb
+        # Must match the version in gradle/wrapper/gradle-wrapper.properties.
+        # Bumping the wrapper? Update both the URL and sha256 here.
+        url: https://services.gradle.org/distributions/gradle-9.5.1-all.zip
+        sha256: c72fb9991f6025cbe337d52ba77e531b3faf62bdd3e348fe1ccee9f51c71adb0
         dest: "gradle/wrapper"
-        dest-filename: "gradle-bin.zip"
+        dest-filename: "gradle-all.zip"
       - flatpak-sources.json