fix(tui): repaint + sync mouse mode when display.mouse_tracking changes

Two interacting bugs left the TUI blank when `display.mouse_tracking`
switched at runtime (config edit, /mouse <preset>):

1. AlternateScreen's effect re-runs on every `mouseTracking` change,
   tearing down and re-entering the alt screen. After re-entry, ink's
   frame buffers are reset by `resetFramesForAltScreen()` but nothing
   schedules the follow-up render — the alt screen sits blank until
   some other state change happens to trigger one. Add a
   `scheduleRender()` in `setAltScreenActive`'s active=true branch so
   the freshly-entered alt screen gets a full repaint immediately.

2. `setAltScreenActive` early-returns when `active` hasn't changed,
   which silently drops a `mouseTracking` change if the cleanup→setup
   pair somehow leaves `altScreenActive` already true. Call
   `setAltScreenMouseTracking` explicitly from the AlternateScreen
   effect so the in-memory mode and terminal DECSET sequence stay in
   sync regardless of how `setAltScreenActive` resolved (the call is a
   no-op when the mode is unchanged).

ui-tui/packages/hermes-ink/src/ink/components/AlternateScreen.tsx

@@ -75,6 +75,7 @@ export function AlternateScreen(t0: Props) {
           (enableMouse || DISABLE_MOUSE_TRACKING)
       )
       ink?.setAltScreenActive(true, mouseTracking)
+      ink?.setAltScreenMouseTracking(mouseTracking)
 
       return () => {
         ink?.setAltScreenActive(false)

ui-tui/packages/hermes-ink/src/ink/ink.tsx

@@ -1272,6 +1272,7 @@ export default class Ink {
 
     if (active) {
       this.resetFramesForAltScreen()
+      this.scheduleRender()
     } else {
       this.repaint()
     }