build: resolve lint warnings and enforce warnings-as-errors

Disable GradleDependency nag; enable lint and Kotlin warnings-as-errors.

Author: ajsb85

.github/workflows/ci.yml

@@ -26,8 +26,10 @@ jobs:
       - uses: android-actions/setup-android@v4
       - name: Install SDK packages
         run: sdkmanager "platforms;android-35" "build-tools;36.0.0"
-      - name: Test and assemble
-        run: ./gradlew :cobs:testDebugUnitTest :cobs:assembleRelease --console=plain
+      - name: Test, lint, and assemble
+        run: >-
+          ./gradlew :cobs:testDebugUnitTest :cobs:lint :cobs:assembleRelease
+          --console=plain
       - name: Upload AAR artifact
         uses: actions/upload-artifact@v7
         with:

cobs/build.gradle.kts

@@ -33,6 +33,16 @@ android {
         }
     }
 
+    lint {
+        // Fail the build on any real lint issue.
+        abortOnError = true
+        warningsAsErrors = true
+        // GradleDependency only nags that a newer compileSdk/dependency exists;
+        // this pure-Kotlin library uses no Android APIs, so the compileSdk level
+        // is immaterial and version bumps are made deliberately.
+        disable += "GradleDependency"
+    }
+
     publishing {
         singleVariant("release") {
             withSourcesJar()
@@ -43,6 +53,7 @@ android {
 kotlin {
     compilerOptions {
         jvmTarget = JvmTarget.JVM_17
+        allWarningsAsErrors = true
     }
 }