Fix master compilation after bad story 86 squash merge revert

The revert of story 86's merge left broken code from stories 131/135
that depended on it. Removed dead inline event dispatch (referencing
undefined event_type, pty_writer, PermissionReqMsg), added activity_tx
to process_json_event, and removed unused permission_tx parameter from
chat_stream/chat (permissions go through MCP, not PTY).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/http/ws.rs

@@ -247,7 +247,6 @@ pub async fn ws_handler(ws: WebSocket, ctx: Data<&Arc<AppContext>>) -> impl poem
                                 tool_name: tool_name.to_string(),
                             });
                         },
-                        Some(perm_tx),
                     );
                     tokio::pin!(chat_fut);