Add notification docs and update iOS project

Delete obsolete docs/app_erview.md and add a new comprehensive docs/notification.md covering flutter_local_notifications setup, platform configuration, and a reusable NotificationService implementation. Update ios/Runner.xcodeproj/project.pbxproj to add empty inputPaths/outputPaths for CocoaPods build phases and set Xcode metadata (INFOPLIST_KEY_CFBundleDisplayName = "Flutter Starter", MARKETING_VERSION = 1.0.0) across build configurations, along with other build settings adjustments.

Author: haaris94