fix: clipboard fallback for insecure contexts, session rename via sessions.patch

- Add copyToClipboard utility with execCommand fallback for HTTP deployments (#76)
- Replace all navigator.clipboard.writeText calls with copyToClipboard
- Session rename now persists server-side via sessions.patch (#78)
- Pass onRename callback from App to Sidebar

src/lib/clipboard.ts

@@ -0,0 +1,35 @@
+/**
+ * Copy text to clipboard with fallback for insecure contexts.
+ * navigator.clipboard requires HTTPS or localhost; falls back to
+ * a temporary textarea + execCommand('copy') for HTTP deployments.
+ */
+export async function copyToClipboard(text: string): Promise<boolean> {
+  // Try the modern API first (requires secure context)
+  if (navigator.clipboard?.writeText) {
+    try {
+      await navigator.clipboard.writeText(text);
+      return true;
+    } catch {
+      // Fall through to legacy method
+    }
+  }
+
+  // Fallback: temporary textarea + execCommand
+  try {
+    const textarea = document.createElement('textarea');
+    textarea.value = text;
+    // Move off-screen to avoid visual flash
+    textarea.style.position = 'fixed';
+    textarea.style.left = '-9999px';
+    textarea.style.top = '-9999px';
+    textarea.style.opacity = '0';
+    document.body.appendChild(textarea);
+    textarea.focus();
+    textarea.select();
+    const ok = document.execCommand('copy');
+    document.body.removeChild(textarea);
+    return ok;
+  } catch {
+    return false;
+  }
+}