fix(server): rebind message-stream upstreams after a managed OpenCode restart

When the managed OpenCode process exits but a server survives on the old
port (Windows: killProcessOnPort is a no-op, so the orphaned process tree
keeps the port), restartOpenCode() times out waiting for the port and
spawns a fresh server on a NEW port. HTTP/proxy traffic follows the new
port, but the global message-stream hub's upstream SSE reader stays pinned
to the old server's /global/event stream — that connection never closes —
so new events never reach the UI and the chat stops updating until the
app is restarted (#2638).

Lifecycle now fires an optional onOpenCodeRestarted hook after a
successful managed restart; index.js wires it to the new
messageStreamRuntime.rebindUpstream(), which restarts the shared hub
(its reader re-dials buildOpenCodeUrl → the current port) and closes
directory-scoped sockets so their per-connection readers rebuild against
the new port. External servers are untouched (their port cannot change).

Fixes #2638

packages/web/server/index.js

@@ -1079,6 +1079,19 @@ const openCodeLifecycleRuntime = createOpenCodeLifecycleRuntime({
     }
     return [...new Set(directories)];
   },
+  // A managed restart can move OpenCode to a NEW port (the old one may stay
+  // occupied by an orphaned process, e.g. killProcessOnPort is a no-op on
+  // Windows). Rebind the message-stream upstream readers to the current port
+  // so the UI keeps receiving events instead of staying pinned to the old
+  // process (#2638). The runtime is created later by the startup pipeline;
+  // by the time any restart runs, it is assigned.
+  onOpenCodeRestarted: () => {
+    try {
+      messageStreamRuntime?.rebindUpstream();
+    } catch (error) {
+      console.warn('Failed to rebind message stream after OpenCode restart:', error?.message ?? error);
+    }
+  },
   getManagedOpenCodeEnv: async () => {
     const settings = await readSettingsFromDiskMigrated().catch(() => null);
     const managedEnv = settings?.agentControlToolEnabled === false