[FEATURE] Add managed trash-bag content wrappers

[ifBars]

What would you like to see?

Add a managed wrapper and registry for existing native TrashBag instances.

The initial API should expose:

• stable trash identity/GUID and world position;
• the current wrapped property when available;
• an immutable contents snapshot using TrashContentEntry-style managed values;
• total size and total value;
• destruction notification and active-bag enumeration;
• a server-authoritative destroy operation consistent with other trash wrappers.

Why would this help?

The trash-container API delivered in #240 exposes container contents and bagging, but the resulting world trash bag is still only accessible through native ScheduleOne.Trash.TrashBag and TrashContent. Cleanup, hauling, recycler, employee-task, and UI mods need to inspect what a bag contains after it leaves a container.

Extra Context (Optional)

Keep arbitrary content mutation, custom bag persistence, custom replication, and replacement bag prefabs out of the first version. Reuse existing S1API trash content value types where practical.

Validate bag creation from containers, contents snapshots, destruction, save reload, and host/client visibility separately on Mono and IL2CPP.