Run executables directly (#645)

- Apps can be launched directly from file paths (including Files app support)
- Added executable detection to identify unsupported or invalid binaries before launch.
- App startup is now streamlined through separate registered-app and direct-execution interfaces.
- Existing app launch points were migrated to the updated startup APIs.

Modules/app-module/tests/source/arguments_test.cpp

@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: Apache-2.0
+#include "doctest.h"
+
+#include <app/private/arguments.h>
+
+#include <cstring>
+
+TEST_CASE("app_arguments_copy returns NULL for argc <= 0") {
+    const char* const argv[] = { "a" };
+    CHECK_EQ(app_arguments_copy(0, argv), nullptr);
+    CHECK_EQ(app_arguments_copy(-1, argv), nullptr);
+    CHECK_EQ(app_arguments_copy(0, nullptr), nullptr);
+}
+
+TEST_CASE("app_arguments_copy deep-copies argv") {
+    const char* const argv[] = { "one", "two", "three" };
+    char** copy = app_arguments_copy(3, argv);
+    REQUIRE_NE(copy, nullptr);
+
+    CHECK_NE(static_cast<const void*>(copy[0]), static_cast<const void*>(argv[0]));
+    CHECK_EQ(std::strcmp(copy[0], "one"), 0);
+    CHECK_EQ(std::strcmp(copy[1], "two"), 0);
+    CHECK_EQ(std::strcmp(copy[2], "three"), 0);
+    CHECK_EQ(copy[3], nullptr);
+
+    app_arguments_free(3, copy);
+}
+
+TEST_CASE("app_arguments_copy handles an empty string argument") {
+    const char* const argv[] = { "" };
+    char** copy = app_arguments_copy(1, argv);
+    REQUIRE_NE(copy, nullptr);
+    CHECK_EQ(std::strcmp(copy[0], ""), 0);
+    CHECK_EQ(copy[1], nullptr);
+    app_arguments_free(1, copy);
+}
+
+TEST_CASE("app_arguments_free is a no-op for count 0 / null values") {
+    app_arguments_free(0, nullptr);
+}