[Bug] Homebrew {{scalevalue}} fails at levels above highest Level Scaling entry

When using {{scalevalue}} in a homebrew subclass action snippet, the value fails to resolve on the character sheet if the character's level is higher than the highest Level Scaling entry defined on the feature.

Steps to Reproduce:

1. Create a homebrew subclass with a class feature that has Level Scaling entries (Fixed Value type) at levels 3, 7, 10, 15, and 18.

2. Create an Action on that feature with a snippet using {{scalevalue}} (e.g., "{{scalevalue}}d6 extra damage").

3. Add Level Overrides on the Action at the same levels (7, 10, 15, 18).

4. Assign the subclass to a character and level the character to 20.

Expected Behavior:

At level 20, {{scalevalue}} should resolve to the value from the highest defined entry (level 18, value 5), displaying "5d6 extra damage" on the character sheet.

Actual Behavior:

The character sheet displays: "scalevalue - Has level scale, but no dice value available d6 extra damage" — the snippet breaks completely instead of carrying forward the last defined value.

Workaround:

Add an explicit Level Scaling entry at level 20 with the same Fixed Value as level 18 (and a matching Level Override on the Action). This resolves the issue after propagation.

Suggested Fix:

When the character's level exceeds the highest Level Scaling entry, the system should fall back to the value from the highest defined level rather than failing. This is the expected behavior in most scaling/inheritance systems and would prevent homebrew content from silently breaking at higher levels.