feat(frontend): new strip components, suggestions dropdown, empty state

CorrespondenzPersonBar (Row 1), CorrespondenzFilterControls (Row 2 with
live count + sort), CorrespondentSuggestionsDropdown (fetch-on-focus,
keyboard nav), SinglePersonHintBar, CorrespondenzEmptyState (recent
persons from localStorage). New i18n shim in messages-extra.ts until
root-owned paraglide files can be regenerated.

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

frontend/src/lib/messages-extra.ts

@@ -0,0 +1,37 @@
+/**
+ * Extra message functions for i18n keys added after the last paraglide compile.
+ *
+ * TODO: Remove this file once the root-owned paraglide files in src/lib/paraglide/
+ * are regenerated (run `npm run dev` or the paraglide compile step as the owning user).
+ * At that point, these functions will be generated into _index.js and the components
+ * that import from here should switch back to importing from $lib/paraglide/messages.js.
+ *
+ * Note: these fall back to German only — locale switching is handled by the generated
+ * paraglide files, not this shim.
+ */
+
+// Svelte auto-escapes interpolated values — do not use {@html} with these strings.
+
+export const conv_hint_single_person = (inputs: { name: string }) =>
+	`Alle Briefe von ${inputs.name} — wähle einen Korrespondenten oben um einzugrenzen`;
+
+export const conv_hint_single_person_filtered = (inputs: {
+	name: string;
+	from: string;
+	to: string;
+	sortLabel: string;
+}) => `Alle Briefe von ${inputs.name} · ${inputs.from}–${inputs.to} · ${inputs.sortLabel}`;
+
+export const conv_strip_period = () => 'Zeitraum';
+export const conv_strip_from_placeholder = () => 'Von…';
+export const conv_strip_to_placeholder = () => 'Bis…';
+export const conv_strip_all_correspondents = () => 'Alle Korrespondenten';
+export const conv_strip_sort_newest = () => 'Neueste';
+export const conv_strip_sort_oldest = () => 'Älteste';
+export const conv_suggestions_heading = () => 'Häufigste Korrespondenten';
+export const conv_suggestions_all_label = (inputs: { name: string }) =>
+	`Alle Korrespondenten von ${inputs.name}`;
+export const conv_letters_count = (inputs: { count: number }) => `${inputs.count} Briefe`;
+export const conv_empty_search_placeholder = () => 'Person suchen…';
+export const conv_empty_recent_label = () => 'Zuletzt geöffnet';
+export const conv_no_party = () => '—';