v0.0.7 - Fix ownership validation error
Bug: Foundry v13 V2 forms use -10 as the 'no change' sentinel in permission dropdowns. Our code only filtered -1 (the V1 'inherit' value), so -10 got passed through as an ownership level. Foundry rejected it: ownership: is not a mapping of user IDs and document permission levels.
Fix: Now only applies concrete permission levels (0=None, 1=Limited, 2=Observer, 3=Owner). Any other value (-1, -10, etc.) is skipped with a log message.
Also confirms v0.0.6 submit listener approach works - cascade now fires correctly on Foundry v13.