Fix: Handle empty string initialization for API key expire parameter

- Updated initialization logic to handle both null and invalid date values (including empty strings)
- Removed the check for expirationSelect !== null to allow proper initialization when "Never" is selected
- Added isValidDate check before ISO date conversion to prevent converting invalid dates to 'n/a'
- This fixes the issue where API keys couldn't be created with "Never" expiration when the parent component initializes expire as an empty string

Co-authored-by: stnguyen90 <1477010+stnguyen90@users.noreply.github.com>

Author: Copilot

src/lib/components/expirationInput.svelte

@@ -123,8 +123,8 @@
     let hasUserInteracted = false;
 
     $: {
-        // Set initial value if value is null on first load
-        if (!initialized && value === null && expirationSelect !== null) {
+        // Set initial value if value is null or invalid on first load
+        if (!initialized && (value === null || !isValidDate(value))) {
             value = expirationSelect === 'custom' ? expirationCustom : expirationSelect;
             initialized = true;
         }
@@ -134,8 +134,8 @@
             value = expirationSelect === 'custom' ? expirationCustom : expirationSelect;
         }
 
-        // Only convert to ISO date if value is not null
-        if (value !== null) {
+        // Only convert to ISO date if value is not null and is a valid date
+        if (value !== null && isValidDate(value)) {
             value = toLocaleDateISO(new Date(value).getTime());
         }
     }