## Summary
Converts `RewardGump` and the inner `RewardConfirmGump` from legacy `Gump` to `DynamicGump` with the static `DisplayTo` entry-point pattern.
Both gumps have variable per-instance layout — the reward grid loops over `_rewards` and adds `AddItem(itemID, hue)` / `AddTooltip(tooltipID)` calls whose values are baked into the layout buffer per entry, so a cached static layout would be incorrect. DynamicGump is the right choice and avoids the placeholder dance for non-text values.
Constructors are private; `DisplayTo` validates `NetState`, null `rewards`/`onPicked`, and empty arrays before constructing.
Builder labels use `$"{value}"` interpolated-string-handler form for zero-allocation text.
### Summary
- Fixes an issue that causes CUO to crash due to bad string caching in static gumps
- Fixes wrong/bad 16bit html gump hues.
- Moves `C16232` (16-bit to 32-bit) and `C32216` (32-bit to 16-bit) to Utility class for broader use.
TODO:
- Some gumps have different 32bit (for string content) vs 16bit (for localized content) strings. Does this matter?
