feat: theme-driven chrome, customizable tab accent, UI polish

- Sidebar/tab bars/dividers/settings dialog follow the terminal theme
- Tab accent color customizable in theme settings (color picker)
- Title bar shows the app icon; Material Dark is the default theme
- Slimmer rectangular tabs (28px), slate scrollbars, visible pane dividers
- Fix pure-black xterm viewport gaps after pane resize

package.json

@@ -1,7 +1,7 @@
 {
   "name": "open-terminal",
   "productName": "OpenTerminal",
-  "version": "1.0.1",
+  "version": "1.0.2",
   "description": "Open-source terminal with SSH, split panes, themes and fonts",
   "main": "out/main/index.js",
   "author": "Bill",