feat(firmware): add OTA updater library skeleton with version comparison

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

firmware/test/test_ota/test_version.cpp

@@ -0,0 +1,44 @@
+// firmware/test/test_ota/test_version.cpp
+#include <unity.h>
+
+// Pull in the function under test — include .cpp directly for native builds
+// so we don't need a separate compilation unit per test.
+#define NATIVE_TEST
+#include "../../lib/ota_updater/ota_updater.cpp"
+
+void setUp() {}
+void tearDown() {}
+
+void test_remote_newer_patch() {
+    TEST_ASSERT_TRUE(ota_version_newer("1.0.0", "1.0.1"));
+}
+void test_remote_newer_minor() {
+    TEST_ASSERT_TRUE(ota_version_newer("1.0.9", "1.1.0"));
+}
+void test_remote_newer_major() {
+    TEST_ASSERT_TRUE(ota_version_newer("0.9.9", "1.0.0"));
+}
+void test_same_version() {
+    TEST_ASSERT_FALSE(ota_version_newer("1.2.3", "1.2.3"));
+}
+void test_remote_older() {
+    TEST_ASSERT_FALSE(ota_version_newer("1.2.3", "1.2.2"));
+}
+void test_malformed_current() {
+    TEST_ASSERT_FALSE(ota_version_newer("bad", "1.0.0"));
+}
+void test_malformed_remote() {
+    TEST_ASSERT_FALSE(ota_version_newer("1.0.0", "bad"));
+}
+
+int main() {
+    UNITY_BEGIN();
+    RUN_TEST(test_remote_newer_patch);
+    RUN_TEST(test_remote_newer_minor);
+    RUN_TEST(test_remote_newer_major);
+    RUN_TEST(test_same_version);
+    RUN_TEST(test_remote_older);
+    RUN_TEST(test_malformed_current);
+    RUN_TEST(test_malformed_remote);
+    return UNITY_END();
+}