fix(live-class): use emitted value from timezone Combobox

[nathanheintz]

The timezone Combobox handler treated the emitted payload as an option object and read opt.value. frappe-ui's Combobox declares defineModel<string | null>(), so update:modelValue emits the value string — opt.value is undefined.

Selecting a timezone therefore cleared liveClass.timezone. Since the field is required, saving then failed validation with a 500.

Read the emitted string directly.

[greptile-apps]

Confidence Score: 5/5

Safe to merge — single targeted fix that correctly reads the emitted string from the Combobox.

The change is minimal and directly addresses the root cause: the Combobox emits a plain string, not an option object, so reading it directly is correct. No other logic is touched.

No files require special attention.

_{Reviews (1): Last reviewed commit: "fix(live-class): use emitted value from ..." | Re-trigger Greptile}