Implemented multi-binary app packaging (#648)

Modules/app-module/source/paths.cpp

@@ -6,6 +6,27 @@
 #include <tactility/paths.h>
 
 #include <cstdio>
+#include <string>
+
+namespace {
+
+// manifest.location.location is the fully-resolved binary file path
+// ({install_dir}/bin/<platform>/<binary>.{elf,so} - see app_resolve_binary_path()), not the
+// install directory itself - strip that fixed 3-segment suffix to recover it.
+bool app_get_install_dir_from_binary_path(const char* binary_path, std::string& out_install_dir) {
+    std::string path = binary_path;
+    for (int i = 0; i < 3; i++) {
+        auto separator = path.find_last_of('/');
+        if (separator == std::string::npos) {
+            return false;
+        }
+        path = path.substr(0, separator);
+    }
+    out_install_dir = path;
+    return true;
+}
+
+} // namespace
 
 extern "C" {
 
@@ -46,7 +67,12 @@ error_t app_paths_get_assets_directory(const char* app_id, char* out_path, size_
         return ERROR_NOT_FOUND;
     }
 
-    int written = std::snprintf(out_path, out_path_size, "%s/assets", static_cast<const char*>(manifest.location.location));
+    std::string install_dir;
+    if (!app_get_install_dir_from_binary_path(static_cast<const char*>(manifest.location.location), install_dir)) {
+        return ERROR_NOT_FOUND;
+    }
+
+    int written = std::snprintf(out_path, out_path_size, "%s/assets", install_dir.c_str());
     if (written < 0 || (size_t)written >= out_path_size) {
         return ERROR_BUFFER_OVERFLOW;
     }