refactor(common): replace Timber with SLF4J

`:common` will be moved to a `java-library`. SLF4J is bridged to Timber
via slf4j-timber in the app, so logs will continue to work.

Due to this, fewer classes will need to move to `:common:android`

Using 1.7.30 as this is the current transitive dependency

Assisted-by: Claude Opus 4.6

Author: david-allison

common/build.gradle.kts

@@ -50,6 +50,7 @@ dependencies {
     implementation(libs.androidx.appcompat)
     implementation(libs.google.material)
     implementation(libs.jakewharton.timber)
+    implementation(libs.slf4j.api)
     testImplementation(libs.junit.jupiter)
     testImplementation(libs.junit.vintage.engine)
     testImplementation(libs.hamcrest)
@@ -60,6 +61,7 @@ dependencies {
 
     testFixturesImplementation(libs.hamcrest)
     testFixturesImplementation(libs.jakewharton.timber)
+    testFixturesImplementation(libs.slf4j.api)
     testFixturesImplementation(libs.androidx.annotation)
     // Required so the ExperimentalCoroutinesApi opt-in (applied globally) doesn't cause
     // an "unresolved" warning, which is treated as an error due to allWarningsAsErrors

common/src/main/java/com/ichi2/anki/common/utils/TestUtils.kt

@@ -13,7 +13,9 @@
  */
 package com.ichi2.anki.common.utils
 
-import timber.log.Timber
+import org.slf4j.LoggerFactory
+
+private val logger = LoggerFactory.getLogger("TestUtils")
 
 /** make default HTML / JS debugging true for debug build and disable for unit/android tests
  * isRunningAsUnitTest checks if we are in debug or testing environment by checking if org.junit.Test class
@@ -25,9 +27,9 @@ val isRunningAsUnitTest: Boolean
         try {
             Class.forName("org.junit.Test")
         } catch (ignored: ClassNotFoundException) {
-            Timber.d("isRunningAsUnitTest: %b", false)
+            logger.debug("isRunningAsUnitTest: {}", false)
             return false
         }
-        Timber.d("isRunningAsUnitTest: %b", true)
+        logger.debug("isRunningAsUnitTest: {}", true)
         return true
     }

common/src/testFixtures/java/com/ichi2/testutils/FileSystemUtils.kt

@@ -19,16 +19,18 @@ package com.ichi2.testutils
 import androidx.annotation.CheckResult
 import org.hamcrest.CoreMatchers
 import org.hamcrest.MatcherAssert
-import timber.log.Timber
+import org.slf4j.LoggerFactory
 import java.io.File
 import kotlin.io.path.createTempDirectory
 import kotlin.io.path.pathString
 
 /** Utilities which assist testing changes to files/directories */
+private val logger = LoggerFactory.getLogger(FileSystemUtils::class.java)
+
 @Suppress("unused")
 object FileSystemUtils {
     /**
-     * Prints a directory structure using [Timber.d]
+     * Prints a directory structure
      * @param description The prefix to print before the tree is listed
      * @param file the root of the tree to print
      *
@@ -47,7 +49,7 @@ object FileSystemUtils {
         description: String,
         file: File,
     ) {
-        Timber.d("$description: $file\n${printDirectoryTree(file)}")
+        logger.debug("$description: $file\n${printDirectoryTree(file)}")
     }
 
     /** from https://stackoverflow.com/a/13130974/ */
@@ -135,7 +137,7 @@ fun createTransientFile(
 fun File.createTransientDirectory(name: String): File {
     File(this, name).also { directory ->
         directory.deleteOnExit()
-        Timber.d("test: creating $directory")
+        logger.debug("test: creating $directory")
         MatcherAssert.assertThat("directory should have been created", directory.mkdirs(), CoreMatchers.equalTo(true))
         return directory
     }

gradle/libs.versions.toml

@@ -115,6 +115,8 @@ searchpreference = "2.7.3"
 seismic = "1.0.3"
 sharedPreferencesMock = "1.2.4"
 slackKeeper = "0.16.1"
+# https://github.com/qos-ch/slf4j
+slf4j = "1.7.30"
 slf4jTimber = "3.1"
 timber = "5.0.1"
 # https://github.com/Triple-T/gradle-play-publisher/releases
@@ -176,6 +178,7 @@ android-lint-tests = { module = "com.android.tools.lint:lint-tests", version.ref
 protobuf-kotlin-lite = { module = "com.google.protobuf:protobuf-kotlin-lite", version.ref = "protobufKotlinLite" }
 search-preference = { module = "com.github.ByteHamster:SearchPreference", version.ref = "searchpreference" }
 seismic = { module = "com.squareup:seismic", version.ref = "seismic" }
+slf4j-api = { module = "org.slf4j:slf4j-api", version.ref = "slf4j" }
 slf4j-timber = { module = "com.arcao:slf4j-timber", version.ref = "slf4jTimber" }
 jakewharton-timber = { module = "com.jakewharton.timber:timber", version.ref = "timber" }
 androidx-work-runtime = { group = "androidx.work", name = "work-runtime-ktx", version.ref = "androidxWork" }