fix(electrobun): defer xterm.open() until container visible (fixes splash crash)

ui-electrobun/src/mainview/Terminal.svelte

@@ -60,8 +60,30 @@
       showPlaceholder: true,
     }));
 
-    term.open(termEl);
-    fitAddon.fit();
+    // Defer open if container isn't visible yet (e.g., behind splash)
+    const tryOpen = () => {
+      try {
+        term.open(termEl);
+        fitAddon.fit();
+      } catch (e) {
+        console.warn('[Terminal] open failed, retrying in 500ms:', (e as Error).message);
+        setTimeout(tryOpen, 500);
+      }
+    };
+    if (termEl.offsetParent !== null) {
+      tryOpen();
+    } else {
+      // Container not visible — wait for it
+      const observer = new IntersectionObserver((entries) => {
+        if (entries[0]?.isIntersecting) {
+          observer.disconnect();
+          tryOpen();
+        }
+      });
+      observer.observe(termEl);
+      // Fallback: try after 2s regardless
+      setTimeout(() => { observer.disconnect(); tryOpen(); }, 2000);
+    }
 
     // ── Read cursor/scrollback settings ─────────────────────────────────