Enhance backend server resource path resolution in Tauri

- Updated logic to include additional paths for the backend server executable, accommodating the AppImage structure and ensuring resources are correctly located in both Windows and non-Windows environments.
- Improved comments for clarity on resource directory handling, enhancing maintainability and understanding of the code.

These changes improve the reliability of backend server execution by ensuring all potential resource locations are checked.

Author: Firstp1ck

frontend/src-tauri/src/lib.rs

@@ -441,13 +441,18 @@ fn start_backend_server(
 
   // Try Tauri resource resolution (for bundled resources)
   if let Ok(resource_dir) = app.path().resource_dir() {
+    // Resources may be in a 'resources' subdirectory (AppImage structure)
     #[cfg(windows)]
     {
+      possible_exe_paths.push(resource_dir.join("resources").join("backend-server.exe"));
+      possible_exe_paths.push(resource_dir.join("resources").join("backend-server"));
       possible_exe_paths.push(resource_dir.join("backend-server.exe"));
       possible_exe_paths.push(resource_dir.join("backend-server"));
     }
     #[cfg(not(windows))]
     {
+      possible_exe_paths.push(resource_dir.join("resources").join("backend-server"));
+      possible_exe_paths.push(resource_dir.join("resources").join("backend-server.exe"));
       possible_exe_paths.push(resource_dir.join("backend-server"));
       possible_exe_paths.push(resource_dir.join("backend-server.exe"));
     }
@@ -982,13 +987,18 @@ pub fn run() {
               warn!("Resource directory does not exist: {:?}", resource_dir);
             }
             // Prioritize platform-specific executables
+            // Note: Resources may be in a 'resources' subdirectory (AppImage structure)
             #[cfg(windows)]
             {
+              possible_exe_paths.push(resource_dir.join("resources").join("backend-server.exe"));
+              possible_exe_paths.push(resource_dir.join("resources").join("backend-server"));
               possible_exe_paths.push(resource_dir.join("backend-server.exe"));
               possible_exe_paths.push(resource_dir.join("backend-server"));
             }
             #[cfg(not(windows))]
             {
+              possible_exe_paths.push(resource_dir.join("resources").join("backend-server"));
+              possible_exe_paths.push(resource_dir.join("resources").join("backend-server.exe"));
               possible_exe_paths.push(resource_dir.join("backend-server"));
               possible_exe_paths.push(resource_dir.join("backend-server.exe"));
             }
@@ -1031,6 +1041,11 @@ pub fn run() {
             if let Ok(appdir) = std::env::var("APPDIR") {
               info!("AppImage APPDIR: {}", appdir);
               let appdir_path = PathBuf::from(&appdir);
+              // AppImage structure: usr/lib/ProductName/resources/backend-server
+              possible_exe_paths.push(appdir_path.join("usr").join("lib").join("Budget Planer").join("resources").join("backend-server"));
+              possible_exe_paths.push(appdir_path.join("usr").join("lib").join("budget-planer").join("resources").join("backend-server"));
+              possible_exe_paths.push(appdir_path.join("usr").join("lib").join("com.budgetplaner").join("resources").join("backend-server"));
+              // Also check without resources subdirectory
               possible_exe_paths.push(appdir_path.join("usr").join("lib").join("backend-server"));
               possible_exe_paths.push(appdir_path.join("usr").join("share").join("backend-server"));
               possible_exe_paths.push(appdir_path.join("resources").join("backend-server"));