refactor(logging): use Timber instead of Kermit

Android-only project, so Timber (the de-facto Android logging lib) fits better than the
KMP-oriented Kermit.

- Catalog: kermit -> timber (com.jakewharton.timber:timber 5.0.1).
- core:data: Ktor Logging bridged to Timber; safeCall logs via Timber.
- app: plant Timber.DebugTree() in debug only (buildConfig enabled for BuildConfig.DEBUG).

core/data/build.gradle.kts

@@ -18,5 +18,5 @@ android {
 
 dependencies {
     implementation(project(":core:domain"))
-    implementation(libs.kermit)
+    implementation(libs.timber)
 }