Grund: Compose-app med login mot gym-API:t, VS Code-task och CI-release

- Kotlin + Jetpack Compose + Material 3, minSdk 31 (Android 12)
- GraphQL-klient (OkHttp) med login/refresh/validate/logout som webben
- Tokenlagring i DataStore, auto-refresh av JWT
- Signering via gitignorerad signing/ lokalt och Actions-secrets i CI
- VS Code build-task -> build/FitnessDroid.apk
- Gitea Actions: bygger APK på Pi5 (arm64, aapt2-override) och publicerar
  rullande latest-release

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Kf4MAbZ3c3B4Xy5XfuGsCP

app/src/main/java/eu/brassepc/fitnessdroid/data/GraphQlClient.kt

@@ -0,0 +1,64 @@
+package eu.brassepc.fitnessdroid.data
+
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.json.JsonObject
+import kotlinx.serialization.json.buildJsonObject
+import kotlinx.serialization.json.jsonArray
+import kotlinx.serialization.json.jsonObject
+import kotlinx.serialization.json.jsonPrimitive
+import kotlinx.serialization.json.put
+import okhttp3.MediaType.Companion.toMediaType
+import okhttp3.OkHttpClient
+import okhttp3.Request
+import okhttp3.RequestBody.Companion.toRequestBody
+import java.util.concurrent.TimeUnit
+
+class GraphQlException(val messages: List<String>) : Exception(messages.joinToString("; "))
+
+/**
+ * Minimal GraphQL-klient över OkHttp. Samma request-form som webbklienten
+ * (gymTrackerApi.js): POST {query, variables} + "Authorization: Bearer <jwt>".
+ */
+class GraphQlClient(private val urlProvider: suspend () -> String) {
+
+    private val http = OkHttpClient.Builder()
+        .connectTimeout(10, TimeUnit.SECONDS)
+        .readTimeout(30, TimeUnit.SECONDS)
+        .build()
+
+    val json = Json { ignoreUnknownKeys = true }
+
+    suspend fun execute(
+        query: String,
+        variables: JsonObject = buildJsonObject {},
+        token: String? = null,
+    ): JsonObject = withContext(Dispatchers.IO) {
+        val body = buildJsonObject {
+            put("query", query)
+            put("variables", variables)
+        }
+        val request = Request.Builder()
+            .url(urlProvider())
+            .post(body.toString().toRequestBody("application/json".toMediaType()))
+            .apply { if (token != null) header("Authorization", "Bearer $token") }
+            .build()
+
+        http.newCall(request).execute().use { response ->
+            val text = response.body?.string().orEmpty()
+            val root = runCatching { json.parseToJsonElement(text).jsonObject }.getOrNull()
+                ?: throw GraphQlException(listOf("HTTP ${response.code}: oväntat svar från servern"))
+
+            root["errors"]?.jsonArray?.takeIf { it.isNotEmpty() }?.let { errors ->
+                throw GraphQlException(
+                    errors.map {
+                        it.jsonObject["message"]?.jsonPrimitive?.content ?: "Okänt fel"
+                    }
+                )
+            }
+            root["data"]?.jsonObject
+                ?: throw GraphQlException(listOf("HTTP ${response.code}: tomt svar från servern"))
+        }
+    }
+}