Migrate framework models to Kotlin and fix build system

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• Complete migration of 138 framework model files from Java to Kotlin
• Updated build.gradle with Kotlin support and dependencies
• Maintained 100% backward compatibility with existing Java code
• Enhanced null safety and reduced boilerplate code
• Fixed Glide annotation processor issues for successful builds

All core models converted including:

• BaseModel, DatabaseHelper, ServerInfo, CertificateInfo
• Repository models (RepoInfoModel, DirentFileModel, etc.)
• Document models (SDoc, FileDetail, Metadata, etc.)
• User & permission models (UserModel, PermissionModel, etc.)
• Search, activity, and transfer models

Build system improvements:

• Resolved missing GlideApp class generation
• Fixed compilation errors and dependency conflicts
• App successfully builds and runs on Android emulators