refactor(web): ClozeCardForm + MultipleChoiceCardForm extrahieren + Import-Bug fixen

- `ClozeCardForm.svelte`: Lückentext-Formular-Sektion aus cards/new herausgezogen
- `MultipleChoiceCardForm.svelte`: MC-Options-Builder (inkl. 85 Zeilen MC-CSS)
  aus cards/new herausgezogen — cards/new: 1010 → 856 Zeilen
- Import-Bug in 9 Dateien behoben: Python-Skript hatte apiErrorMessage-Import
  in mehrzeilige import-Blöcke eingefügt (Syntaxfehler)

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

apps/web/src/lib/components/ClozeCardForm.svelte

@@ -0,0 +1,87 @@
+<script lang="ts">
+	import { t } from '$lib/i18n/index.svelte.ts';
+
+	let {
+		text = $bindable(),
+		extra = $bindable(),
+		clusterIds,
+	}: {
+		text: string;
+		extra: string;
+		clusterIds: string[];
+	} = $props();
+</script>
+
+<label class="field">
+	<span class="field-label">{t('card_new.cloze_text_label')}</span>
+	<textarea
+		bind:value={text}
+		required
+		rows="6"
+		placeholder={t('card_new.cloze_text_placeholder')}
+		class="input mono"
+	></textarea>
+	<span class="field-hint">{t('card_new.cloze_help')}</span>
+	{#if text.trim() && clusterIds.length === 0}
+		<span class="field-error">{t('card_new.cloze_no_clusters')}</span>
+	{:else if clusterIds.length > 0}
+		<span class="field-hint">
+			{t('card_new.cloze_clusters_detected', { n: clusterIds.length, ids: clusterIds.join(', c') })}
+		</span>
+	{/if}
+</label>
+<label class="field">
+	<span class="field-label">{t('card_new.cloze_extra_label')}</span>
+	<textarea
+		bind:value={extra}
+		rows="3"
+		placeholder={t('card_new.cloze_extra_placeholder')}
+		class="input mono"
+	></textarea>
+</label>
+
+<style>
+	.field {
+		display: flex;
+		flex-direction: column;
+		gap: 0.25rem;
+	}
+
+	.field-label {
+		font-size: 0.8125rem;
+		font-weight: 600;
+		color: hsl(var(--color-foreground));
+		letter-spacing: 0.01em;
+	}
+
+	.field-hint {
+		font-size: 0.75rem;
+		color: hsl(var(--color-muted-foreground));
+		line-height: 1.4;
+	}
+
+	.field-error {
+		font-size: 0.75rem;
+		color: hsl(var(--color-error));
+	}
+
+	.input {
+		display: block;
+		width: 100%;
+		border: 1px solid hsl(var(--color-border));
+		border-radius: 0.5rem;
+		background: hsl(var(--color-surface));
+		color: hsl(var(--color-foreground));
+		padding: 0.5rem 0.625rem;
+		font-size: 0.875rem;
+		line-height: 1.5;
+		transition: border-color 0.12s, box-shadow 0.12s;
+		resize: vertical;
+	}
+	.input:focus {
+		outline: none;
+		border-color: hsl(var(--color-primary) / 0.6);
+		box-shadow: 0 0 0 3px hsl(var(--color-primary) / 0.1);
+	}
+	.input.mono { font-family: ui-monospace, 'Cascadia Code', monospace; }
+</style>