feat(search): wire theme chip removal to URL navigation in +page.svelte

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

frontend/src/routes/documents/theme-chip-removal.ts

@@ -0,0 +1,26 @@
+import type { components } from '$lib/generated/api';
+
+type NlQueryInterpretation = components['schemas']['NlQueryInterpretation'];
+
+export function buildThemeRemovalUrl(
+	interp: NlQueryInterpretation,
+	removedTagName: string
+): string {
+	const remaining = interp.resolvedTags.filter((t) => t.name !== removedTagName);
+	const params = new URLSearchParams();
+
+	const resolved = interp.resolvedPersons;
+	if (resolved.length >= 1) params.set('senderId', resolved[0].id);
+	if (resolved.length >= 2) params.set('receiverId', resolved[1].id);
+	if (interp.dateFrom) params.set('from', interp.dateFrom);
+	if (interp.dateTo) params.set('to', interp.dateTo);
+	if (interp.keywordsApplied && interp.keywords.length > 0) {
+		params.set('q', interp.keywords.join(' '));
+	}
+
+	remaining.forEach((tag) => params.append('tag', tag.name));
+	if (remaining.length > 0) params.set('tagOp', 'OR');
+
+	const qs = params.toString();
+	return qs ? `/documents?${qs}` : '/documents';
+}