feat(lotus): tell the host when the call drops, and let it press Reconnect (cinny #318)

After a homeserver stall the frame shows "Connection lost · Reconnect"
while the host kept showing the call as joined, with controls that did
nothing. While the error page is up, report io.lotus.call_error
{ code, recoverable } (and { code: null } when it clears), and accept
io.lotus.reconnect to run the page's own Reconnect / Try again.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/lotus/lotusActions.test.ts

@@ -34,6 +34,7 @@ describe("LotusWidgetActions", () => {
       LotusWidgetActions.SetHotkeys,
       LotusWidgetActions.SetFrameScreenshare,
       LotusWidgetActions.PromptScreenshare,
+      LotusWidgetActions.Reconnect,
     ];
 
     expect(new Set(LOTUS_TO_WIDGET_ACTIONS)).toEqual(new Set(expectedToWidget));
@@ -56,5 +57,6 @@ describe("LotusWidgetActions", () => {
     );
     expect(LOTUS_TO_WIDGET_ACTIONS).not.toContain(LotusWidgetActions.MicLevel);
     expect(LOTUS_TO_WIDGET_ACTIONS).not.toContain(LotusWidgetActions.Hotkey);
+    expect(LOTUS_TO_WIDGET_ACTIONS).not.toContain(LotusWidgetActions.CallError);
   });
 });