[nick2781]

The public entity custom-uint32 setter always returned false, so fields could be created/read but never updated through their matching API.

Look up the existing field, reject missing or differently typed values without mutation, and call the existing unsigned storage setter for valid uint32 fields. Public signatures and layout remain unchanged. Update the Kernel reference in both languages.

Validation:

• The new public-entity test failed on the unchanged stub, then passed with the fix.
• Debug, Release and AddressSanitizer/UndefinedBehaviorSanitizer runs passed: 12 cases / 510 assertions each. Leak detection was disabled.
• Actual Kernel/EntityOperations dynamic libraries verified 0 → UINT32_MAX → 0 on four players and preserved an existing signed value after rejection.
• 157 policy tests, clang-format 18 and Nimbus passed; affected canonical HTML and Markdown were checked.

The branch is normally synchronized with accepted main #172. No other placeholder API, schema, serializer or ownership behavior is changed. Hosted checks remain separate from these local results.