fix(frontend): conversation deletion reappears after refresh for board meetings

Root cause: private board meetings are persisted server-side as soon as
board_started is emitted (portal intercepts and saves the message), but
the frontend left the conversation marked is_local=true. deleteConversation
skipped the server DELETE for local conversations, so only the in-memory
list was updated; the next refresh reloaded the conversation from SQLite.

Changes:
- chatStream.ts: on board_started, mark the conversation is_local=false
  so the server delete is called.
- chatStore.ts: loadConversations() now explicitly sets is_local=false
  for anything returned from the server as a safety net.

Type-check passes (existing unrelated test-file node module errors remain).

src/agentkit/server/frontend/src/stores/chatStore.ts

@@ -209,6 +209,9 @@ export const useChatStore = defineStore("chat", () => {
         // @board meeting (board_started persisted). Frontend uses this
         // to render the "私董会" badge in the sidebar.
         is_board: conv.is_board === true,
+        // Anything returned from the server is already persisted — mark it
+        // non-local so deleteConversation routes to the server endpoint.
+        is_local: false,
       }));
     } catch (error) {
       console.error("Failed to load conversations:", error);

src/agentkit/server/frontend/src/stores/chatStream.ts

@@ -1157,6 +1157,17 @@ export function dispatchWsEvent(
           board_round: 0,
         };
         state.appendMessage(conversationId, startMsg);
+        // Board meetings are persisted server-side as soon as board_started
+        // is emitted (portal intercepts and saves the message). Mark the
+        // conversation non-local so deleteConversation calls the server
+        // instead of only removing it from the local list — otherwise the
+        // conversation reappears on the next refresh.
+        const conv = state.conversations.value.find(
+          (c) => c.id === conversationId,
+        );
+        if (conv) {
+          conv.is_local = false;
+        }
       }
       break;
     }