feat: add Carla plugin host stubs and integration plan

client/tests/test_carla_host.c

@@ -0,0 +1,46 @@
+#include <stdio.h>
+#include "carla_host.h"
+
+static int tests_passed = 0;
+static int tests_failed = 0;
+
+#define ASSERT_EQ(expected, actual, msg) do { \
+    if ((expected) != (actual)) { \
+        fprintf(stderr, "FAIL: %s  (expected %d, got %d)\n", msg, (int)(expected), (int)(actual)); \
+        tests_failed++; \
+    } else { \
+        printf("PASS: %s\n", msg); \
+        tests_passed++; \
+    } \
+} while(0)
+
+static void test_carla_load_null_binary(void)
+{
+    int id = -999;
+    int ret = carla_load(NULL, "someplugin", &id);
+    ASSERT_EQ(-1, ret, "carla_load(NULL, ...) returns -1");
+}
+
+static void test_carla_unload_invalid_id(void)
+{
+    int ret = carla_unload(-1);
+    ASSERT_EQ(-1, ret, "carla_unload(-1) returns -1");
+}
+
+static void test_carla_connect_invalid_id(void)
+{
+    int ret = carla_connect(-1, "out", "looper:in");
+    ASSERT_EQ(-1, ret, "carla_connect(-1, ...) returns -1");
+}
+
+int main(void)
+{
+    printf("=== Carla host stub unit tests ===\n");
+
+    test_carla_load_null_binary();
+    test_carla_unload_invalid_id();
+    test_carla_connect_invalid_id();
+
+    printf("\nResults: %d passed, %d failed\n", tests_passed, tests_failed);
+    return tests_failed > 0 ? 1 : 0;
+}

client/tests/test_client.c

@@ -1,3 +1,4 @@
+#define _POSIX_C_SOURCE 200809L
 #include "tui.h"
 #include <stdio.h>
 #include <stdlib.h>