Enable devtools in release builds + add frontend logging

- Enable Tauri devtools feature so right-click Inspect works in release
- Open devtools automatically on launch for debugging
- Add log_frontend command: frontend can write to ~/.voicetonotes/frontend.log
- Sidecar logs go to %LOCALAPPDATA%/com.voicetonotes.app/sidecar.log
- Frontend logs go to %USERPROFILE%/.voicetonotes/frontend.log

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

src-tauri/src/commands/system.rs

@@ -60,3 +60,18 @@ pub fn llama_list_models() -> Value {
 pub fn get_data_dir() -> String {
     LlamaManager::data_dir().to_string_lossy().to_string()
 }
+
+/// Log a message from the frontend to a file for debugging.
+#[tauri::command]
+pub fn log_frontend(level: String, message: String) {
+    use std::io::Write;
+    let log_path = LlamaManager::data_dir().join("frontend.log");
+    if let Ok(mut file) = std::fs::OpenOptions::new()
+        .create(true)
+        .append(true)
+        .open(&log_path)
+    {
+        let timestamp = chrono::Local::now().format("%Y-%m-%d %H:%M:%S");
+        let _ = writeln!(file, "[{timestamp}] [{level}] {message}");
+    }
+}