fix(electrobun): no double dialog on cancel, browser closes on select + max-height

- pickDirectory: removed Electrobun fallback on zenity cancel (was causing
  second dialog to appear). Cancel = return null, no fallback.
- PathBrowser: handleBrowserSelect closes browser after selection
- PathBrowser container: max-height 16rem with overflow scroll + border

ui-electrobun/src/bun/index.ts

@@ -133,24 +133,15 @@ const rpc = BrowserView.defineRPC<PtyRPCSchema>({
         try {
           const { execSync } = await import("child_process");
           const start = startingFolder?.replace(/^~/, process.env.HOME || "/home") || process.env.HOME || "/home";
-          // zenity --file-selection --directory gives a proper "Select Folder" dialog
-          // with dark theme support, dirs sorted first, and correct title
           const result = execSync(
             `zenity --file-selection --directory --title="Select Project Folder" --filename="${start}/"`,
             { encoding: "utf-8", timeout: 120_000 }
           ).trim();
           return { path: result || null };
-        } catch {
-          // User cancelled or zenity not found — try Electrobun fallback
-          try {
-            const paths = await Utils.openFileDialog({
-              startingFolder: startingFolder || "~/",
-              canChooseFiles: false,
-              canChooseDirectory: true,
-              allowsMultipleSelection: false,
-            });
-            return { path: paths?.[0] ?? null };
-          } catch { return { path: null }; }
+        } catch (e: any) {
+          // zenity exits with code 1 on cancel, code 5 if not found
+          // Do NOT fall back to Electrobun dialog — just return null
+          return { path: null };
         }
       },