Add CI (lint + compile) + Spotless formatting, and apply one-time reformat

.editorconfig

@@ -0,0 +1,21 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+indent_style = space
+indent_size = 4
+
+[*.{kt,kts}]
+# Match IntelliJ IDEA's default Kotlin formatting rather than ktlint's stricter "official" style.
+ktlint_code_style = intellij_idea
+# Compose @Composable functions use PascalCase and components live in multi-declaration files,
+# which the default naming/filename rules would otherwise flag.
+ktlint_function_naming_ignore_when_annotated_with = Composable
+ktlint_standard_function-naming = disabled
+ktlint_standard_filename = disabled
+
+[*.{yml,yaml,json}]
+indent_size = 2

.github/workflows/ci.yml

@@ -0,0 +1,47 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ci-${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build:
+    name: Lint & compile
+    runs-on: ubuntu-latest
+    env:
+      # The com.fastcomments artifacts are public-read on Repsy, so these are optional;
+      # they are forwarded if the secrets happen to be configured.
+      REPSY_USERNAME: ${{ secrets.REPSY_USERNAME }}
+      REPSY_PASSWORD: ${{ secrets.REPSY_PASSWORD }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up JDK 17
+        uses: actions/setup-java@v4
+        with:
+          java-version: '17'
+          distribution: 'temurin'
+
+      - name: Set up Gradle
+        uses: gradle/actions/setup-gradle@v4
+
+      - name: Grant execute permission for gradlew
+        run: chmod +x ./gradlew
+
+      - name: Spotless (formatting check)
+        run: ./gradlew spotlessCheck
+
+      - name: Android Lint
+        run: ./gradlew lintDebug
+
+      - name: Compile (assemble debug)
+        run: ./gradlew assembleDebug

app/build.gradle.kts

@@ -18,12 +18,17 @@ android {
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
     }
 
+    lint {
+        // Snapshot of pre-existing issues so CI only fails on newly introduced ones.
+        baseline = file("lint-baseline.xml")
+    }
+
     buildTypes {
         release {
             isMinifyEnabled = false
             proguardFiles(
                 getDefaultProguardFile("proguard-android-optimize.txt"),
-                "proguard-rules.pro"
+                "proguard-rules.pro",
             )
         }
     }
@@ -79,4 +84,4 @@ dependencies {
     androidTestImplementation(libs.androidx.ui.test.junit4)
     debugImplementation(libs.androidx.ui.tooling)
     debugImplementation(libs.androidx.ui.test.manifest)
-}
+}