fix: allow editing custom email in Select component

When a custom value (not in the items list) is selected, reopening
the dropdown now pre-fills the filter with the current value so users
can directly edit it. Also hide the "Use custom email" create option
when the filter matches the current value, and show the regular
placeholder instead of the value when editing a custom entry.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/lib/components/select/Select.svelte

@@ -95,7 +95,7 @@
 	let inputEl: HTMLInputElement | undefined = $state()
 
 	let processedItems: ProcessedItem<Value>[] = $derived.by(() => {
-		let args = { items, createText, filterText, groupBy, onCreateItem, sortBy }
+		let args = { items, createText, filterText, groupBy, onCreateItem, sortBy, currentValue: value }
 		return untrack(() => processItems(args))
 	})
 
@@ -103,7 +103,15 @@
 		if (filterText) open = true
 	})
 	$effect(() => {
-		if (!open) filterText = ''
+		if (!open) {
+			filterText = ''
+		} else {
+			untrack(() => {
+				if (value && !valueEntry) {
+					filterText = inputText
+				}
+			})
+		}
 	})
 
 	let valueEntry = $derived(value && processedItems?.find((item) => deepEqual(item.value, value)))
@@ -163,7 +171,7 @@
 		bind:value={() => (open ? filterText : inputText), (v) => open && (filterText = v)}
 		placeholder={loading && !value
 			? 'Loading...'
-			: value && !showPlaceholderOnOpen
+			: value && !showPlaceholderOnOpen && !(open && !valueEntry)
 				? inputText
 				: placeholder}
 		style={containerStyle}

frontend/src/lib/components/select/utils.svelte.ts

@@ -4,7 +4,8 @@ export function processItems<Item extends { label?: string; value: any }>({
 	groupBy,
 	sortBy,
 	onCreateItem,
-	createText
+	createText,
+	currentValue
 }: {
 	items?: Item[]
 	filterText?: string
@@ -12,6 +13,7 @@ export function processItems<Item extends { label?: string; value: any }>({
 	sortBy?: (a: Item, b: Item) => number
 	onCreateItem?: (value: string) => void
 	createText?: string
+	currentValue?: any
 }): ProcessedItem<Item['value']>[] {
 	let items2 =
 		items?.map((item) => ({
@@ -28,7 +30,12 @@ export function processItems<Item extends { label?: string; value: any }>({
 	if (sortBy) {
 		items2 = items2?.sort(sortBy)
 	}
-	if (onCreateItem && filterText && !items2.some((item) => item.label === filterText)) {
+	if (
+		onCreateItem &&
+		filterText &&
+		filterText !== currentValue &&
+		!items2.some((item) => item.label === filterText)
+	) {
 		items2.push({
 			label: createText ?? `Add new: "${filterText}"`,
 			value: filterText,