fix: use writable data root for AppImage and packaged builds

AppImage mounts process.resourcesPath as read-only squashfs, causing
all cache/metadata writes to fail. Use a portable data directory next
to the AppImage file instead, and auto-create the directory structure
on first run.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: MrScripty

electron/src/main.ts

@@ -202,9 +202,18 @@ async function initializeBackend(): Promise<void> {
     ? path.join(process.resourcesPath, binaryName)
     : path.join(__dirname, '..', '..', 'rust', 'target', 'release', binaryName);
 
-  const launcherRoot = app.isPackaged
-    ? process.resourcesPath
-    : path.join(__dirname, '..', '..');
+  // Data root: portable (next to AppImage) or project root in dev
+  let launcherRoot: string;
+  if (process.env.APPIMAGE) {
+    // AppImage: store data next to the .AppImage file
+    launcherRoot = path.join(path.dirname(process.env.APPIMAGE), 'pumas-data');
+  } else if (app.isPackaged) {
+    // Other packaged formats (.deb, etc.): use standard user data path
+    launcherRoot = app.getPath('userData');
+  } else {
+    // Development mode: project root
+    launcherRoot = path.join(__dirname, '..', '..');
+  }
 
   pythonBridge = new PythonBridge({
     port: 0,

rust/crates/pumas-rpc/src/main.rs

@@ -80,7 +80,12 @@ async fn main() -> Result<()> {
     info!("Launcher root: {}", launcher_root.display());
 
     // Create the core API instance (model library, system utilities)
-    let api = pumas_library::PumasApi::new(&launcher_root).await?;
+    // Use builder with auto_create_dirs so first-run (e.g. portable AppImage)
+    // creates the directory structure automatically.
+    let api = pumas_library::PumasApi::builder(&launcher_root)
+        .auto_create_dirs(true)
+        .build()
+        .await?;
 
     // Initialize version managers for all supported apps
     let mut version_managers: HashMap<String, VersionManager> = HashMap::new();