Make DevTools a toggle in Settings > Developer tab

- DevTools off by default (no more auto-open on launch)
- New "Developer" tab in Settings with a checkbox to toggle devtools
- Toggle takes effect immediately (opens/closes inspector)
- Setting persists: devtools restored on next launch if enabled
- toggle_devtools Tauri command wraps window.open/close_devtools

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

src-tauri/src/lib.rs

@@ -13,7 +13,7 @@ use commands::project::{
     create_project, delete_project, get_project, list_projects, load_project_file,
     load_project_transcript, save_project_file, save_project_transcript, update_segment,
 };
-use commands::settings::{load_settings, save_settings};
+use commands::settings::{load_settings, save_settings, toggle_devtools};
 use commands::sidecar::{check_sidecar, check_sidecar_update, download_sidecar};
 use commands::system::{
     get_data_dir, llama_list_models, llama_start, llama_status, llama_stop, log_frontend,
@@ -41,8 +41,6 @@ pub fn run() {
             // Set the webview background to match the app's dark theme
             if let Some(window) = app.get_webview_window("main") {
                 let _ = window.set_background_color(Some(Color(10, 10, 35, 255)));
-                // Enable right-click → Inspect (requires "devtools" feature in Cargo.toml)
-                window.open_devtools();
             }
             Ok(())
         })
@@ -74,6 +72,7 @@ pub fn run() {
             download_sidecar,
             check_sidecar_update,
             log_frontend,
+            toggle_devtools,
         ])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");