Fix: Persist ExpandableText state across recomposition

[Sami00777]

Problem
When users scrolled through the series list and returned to top of the screen, the text would collapse back to its truncated state. This occurred because ExpandableText was using remember instead of rememberSaveable, causing state to be lost when items left and re-entered the composition during list scrolling.

Changes

1. Changed expanded from remember to rememberSaveable
2. Changed showReadMore from remember to rememberSaveable

Result
Text expansion state now persists during list scrolling and configuration changes.

1.mp4