Issue #3630631: Label enum prop options with their meta:enum labels in the dialog

Enum prop selects in the dialog, and in a nested component slot, now show each value's meta:enum label, translated with the prop's x-translation-context as core does, instead of the raw value. The stored value does not change. Adds SdcDiscoveryTest::testEnumOptionsUseMetaEnumLabels(), which fails without the fix.

AI usage: AI-Generated: Yes. I used Claude Code (Anthropic) to write the fix and the test. I reproduced the bug and verified the fix in the browser, in English and Portuguese, and reviewed the code.

Closes #3630631