Memory leak: SDK event listeners never unsubscribed in App component

[sauerdaniel]

Problem

The TUI App component subscribes to 6 SDK events but never unsubscribes from them:

• TuiEvent.CommandExecute
• TuiEvent.ToastShow
• TuiEvent.SessionSelect
• SessionApi.Event.Deleted
• SessionApi.Event.Error
• Installation.Event.UpdateAvailable

The sdk.event.on() method returns an unsubscribe function that is being ignored.

Code Location

packages/opencode/src/cli/cmd/tui/app.tsx - lines 557-616

Impact

• Event listeners accumulate over component lifecycle
• Closures retain references preventing garbage collection
• Memory growth in long-running sessions
• Potential duplicate event handling

Relates to #5363

Expected Behavior

Event listeners should be stored and unsubscribed in onCleanup:

const unsubs: (() => void)[] = []

unsubs.push(sdk.event.on(TuiEvent.CommandExecute.type, (evt) => {
  command.trigger(evt.properties.command)
}))

// ... other listeners

onCleanup(() => {
  unsubs.forEach((unsub) => unsub())
})