Take ktfmt's defaults for the Kotlin half

The server half went to rustfmt's defaults earlier today; this is the same
move for the app, and the same reasoning. Kotlin ships no formatter with
the Gradle build, so the question was which to adopt: ktfmt is Kotlin-org
owned now (it moved from facebook/ktfmt), is a formatter rather than a
configurable linter, and has essentially nothing to tune -- which is what
rule 27 is asking for. ktlint's .editorconfig surface is the thing that
rule warns against, and detekt is static analysis, whose job Android Lint
already does here.

One setting, and it is a choice between the tool's own two styles rather
than a tuning: kotlinLangStyle() is the 4-space one, which is what this
code already was. The 2-space default would have reindented every file to
say nothing.

  ./gradlew :androidApp:ktfmtFormat   to apply
  ./gradlew :androidApp:ktfmtCheck    to verify

Formatting only. The one thing worth checking by hand was the generated
PEM constant, since a leading newline there costs Android's
CertificateFactory its preamble sniff and fails at runtime nowhere near
the cause: ktfmt moved `.trimMargin()` onto its own line and left the
template alone, and the regenerated constant still starts at the opening
quotes.

Verified after: ktfmtCheck, compileDebugKotlin and lintDebug all pass, and
the APK builds.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017xn8nHw1tw1R6PtiY1eEtw

app/androidApp/build.gradle.kts

@@ -2,8 +2,18 @@ plugins {
     alias(libs.plugins.androidApplication)
     alias(libs.plugins.composeMultiplatform)
     alias(libs.plugins.composeCompiler)
+    alias(libs.plugins.ktfmt)
 }
 
+// Formatting is the formatter's. The one setting is which of ktfmt's two
+// styles: kotlinlang is the 4-space one, which is what this code already
+// is -- picking the 2-space default would have reindented every file to
+// say nothing. Everything else stays at ktfmt's defaults, deliberately.
+//
+//   ./gradlew :androidApp:ktfmtFormat   to apply
+//   ./gradlew :androidApp:ktfmtCheck    to verify
+ktfmt { kotlinLangStyle() }
+
 // The CA this app pins is baked in at build time from the certificates on
 // the machine doing the build -- `$XDG_CONFIG_HOME/ai-app/certs/ca.pem`,
 // which the server generates on first start. AI_APP_CA overrides the path.
@@ -15,19 +25,18 @@ plugins {
 // is no second trust anchor to get wrong, and no stale paste to notice
 // three days later. It also means the private key never has to exist
 // anywhere near this repo.
-val pinnedCaPath: String = System.getenv("AI_APP_CA")
-    ?: "${System.getenv("XDG_CONFIG_HOME") ?: "${System.getProperty("user.home")}/.config"}" +
-    "/ai-app/certs/ca.pem"
+val pinnedCaPath: String =
+    System.getenv("AI_APP_CA")
+        ?: "${System.getenv("XDG_CONFIG_HOME") ?: "${System.getProperty("user.home")}/.config"}" +
+            "/ai-app/certs/ca.pem"
 
 abstract class GeneratePinnedCert : DefaultTask() {
     /** Where the certificate is looked for, reported in failures. */
-    @get:Input
-    abstract val caPath: Property<String>
+    @get:Input abstract val caPath: Property<String>
 
     /**
-     * The certificate itself, set only when it exists -- so a missing one
-     * produces this task's own instructions rather than Gradle's "no such
-     * input file", which doesn't say what to run.
+     * The certificate itself, set only when it exists -- so a missing one produces this task's own
+     * instructions rather than Gradle's "no such input file", which doesn't say what to run.
      */
     @get:InputFile
     @get:Optional
@@ -35,8 +44,7 @@ abstract class GeneratePinnedCert : DefaultTask() {
     abstract val caCertificate: RegularFileProperty
 
     /** Wired by AGP through `addGeneratedSourceDirectory`. */
-    @get:OutputDirectory
-    abstract val outputDir: DirectoryProperty
+    @get:OutputDirectory abstract val outputDir: DirectoryProperty
 
     @TaskAction
     fun generate() {
@@ -47,7 +55,7 @@ abstract class GeneratePinnedCert : DefaultTask() {
                 "No CA certificate at $path.\n" +
                     "Start ai-server once on this machine first -- it generates the CA the " +
                     "app pins, and the certificate has to exist before an APK can embed it.\n" +
-                    "Set AI_APP_CA=/path/to/ca.pem to build against a different one.",
+                    "Set AI_APP_CA=/path/to/ca.pem to build against a different one."
             )
         }
         val pem = ca.readText().trim()
@@ -69,18 +77,20 @@ abstract class GeneratePinnedCert : DefaultTask() {
             |const val PINNED_CA_PEM = ""${'"'}$pem
             |""${'"'}
             |
-            """.trimMargin(),
+            """
+                .trimMargin()
         )
     }
 }
 
-val generatePinnedCert = tasks.register<GeneratePinnedCert>("generatePinnedCert") {
-    val ca = file(pinnedCaPath)
-    caPath.set(pinnedCaPath)
-    if (ca.isFile) {
-        caCertificate.set(ca)
+val generatePinnedCert =
+    tasks.register<GeneratePinnedCert>("generatePinnedCert") {
+        val ca = file(pinnedCaPath)
+        caPath.set(pinnedCaPath)
+        if (ca.isFile) {
+            caCertificate.set(ca)
+        }
     }
-}
 
 android {
     namespace = "com.example.aiapp"
@@ -93,16 +103,8 @@ android {
         versionCode = 1
         versionName = "1.0"
     }
-    packaging {
-        resources {
-            excludes += "/META-INF/{AL2.0,LGPL2.1}"
-        }
-    }
-    buildTypes {
-        getByName("release") {
-            isMinifyEnabled = false
-        }
-    }
+    packaging { resources { excludes += "/META-INF/{AL2.0,LGPL2.1}" } }
+    buildTypes { getByName("release") { isMinifyEnabled = false } }
     compileOptions {
         sourceCompatibility = JavaVersion.VERSION_21
         targetCompatibility = JavaVersion.VERSION_21