Phase 2: Add Network Bypass for offline mode

- Created OfflineModeManager.smali (toggle offline mode)
- Created OfflineResponseMock.smali (mock API responses)
- Modified NetworkImpl to check offline mode
- Modified MainActivity initialization
- Builds successfully

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

build/apk/res/raw/firebase_crashlytics_keep.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2024 Google LLC
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<resources xmlns:tools="http://schemas.android.com/tools"
+    tools:keep="@string/com.google.firebase.crashlytics_*" />