Show git branch in window title during development (#351)

When running via yarn start on a branch other than master/main, append
the branch name to the window title (e.g. "windows95 (my-feature)").
No-op in packaged builds.

src/main/windows.ts

@@ -1,7 +1,28 @@
 import { BrowserWindow, shell } from "electron";
+import { execFileSync } from "child_process";
+
+import { isDevMode } from "../utils/devmode";
 
 let mainWindow: BrowserWindow | null = null;
 
+function getDevBranchSuffix(): string {
+  if (!isDevMode()) return "";
+
+  try {
+    const branch = execFileSync("git", ["rev-parse", "--abbrev-ref", "HEAD"], {
+      encoding: "utf8",
+    }).trim();
+
+    if (branch && branch !== "master" && branch !== "main") {
+      return ` (${branch})`;
+    }
+  } catch {
+    // git not available or not a repo — ignore
+  }
+
+  return "";
+}
+
 export function getOrCreateWindow(): BrowserWindow {
   if (mainWindow) return mainWindow;
 
@@ -18,6 +39,14 @@ export function getOrCreateWindow(): BrowserWindow {
     },
   });
 
+  const branchSuffix = getDevBranchSuffix();
+  if (branchSuffix) {
+    mainWindow.on("page-title-updated", (event, title) => {
+      event.preventDefault();
+      mainWindow?.setTitle(`${title}${branchSuffix}`);
+    });
+  }
+
   mainWindow.loadFile("./dist/static/index.html");
 
   mainWindow.webContents.on("will-navigate", (event, url) =>