[codex] Fix exception overlay script reload

[S1mplector]

What changed

• Route the runtime exception overlay Reload button through the real scenario reload path.
• Reparse the current script and replace the running scene with its updated content.
• Preserve settings, variables, playback modes, and the nearest available label.
• Refresh the exception overlay when the updated script still fails to load.

Why

The Reload button previously reset the already-built scenario to node zero and called its lifecycle hook again. It never read the edited script, so fixing the source and pressing Reload appeared to do nothing.

Impact

Developers can correct a runtime or parse error on disk and retry directly from the error overlay without restarting the game.

Validation

• ./gradlew :fx:test
• git diff --check