Add ADR 0001 about Java to Kotlin switch

docs/architecture/adr/0001-switch-from-java-to-kotlin.md

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+# 0001 - Switch from Java to Kotlin
+
+## Status
+
+- **Accepted**
+
+## Context
+
+We've been using Java as our primary language for Android development. While Java has served us well, it has certain
+limitations in terms of null safety, verbosity, functional programming, and more. Kotlin, officially supported by
+Google for Android development, offers solutions to many of these issues and provides more modern language features
+that can improve productivity, maintainability, and overall code quality.
+
+## Decision
+
+Switch our primary programming language for Android development from Java to Kotlin. This will involve rewriting our
+existing Java codebase in Kotlin and writing all new code in Kotlin. To facilitate the transition, we will gradually
+refactor our existing Java codebase to Kotlin.
+
+## Consequences
+
+- **Positive Consequences**
+
+  - Improved null safety, reducing potential for null pointer exceptions.
+  - Increased code readability and maintainability due to less verbose syntax.
+  - Availability of modern language features such as coroutines for asynchronous programming, and extension functions.
+  - Officially supported by Google for Android development, ensuring future-proof development.
+
+- **Negative Consequences**
+
+  - The process of refactoring existing Java code to Kotlin can be time-consuming.
+  - Potential for introduction of new bugs during refactoring.