feat(i18n): Export-Modal + Quellenverwaltung + Chat-Widget + Stats-Bar

- Export-Modal: Titel, Bereiche, Format, alle Checkboxes (Zusammenfassung,
  Recherchebericht / Lagebild, Faktencheck, Quellen), PDF/DOCX, Abbrechen,
  Exportieren.
- Quellenverwaltung-Modal: Title, 8 Filter-Labels (sr-only) + 8 Alle-*
  Default-Optionen, Search-Placeholder + Label, + Quelle-Button, Add-
  Form (URL/Erkennen/Name/Kategorie/Typ/RSS-URL/Domain/Notizen +
  Placeholder), Speichern/Abbrechen, Loading-State.
- Stats-Bar (app.js): RSS-Feeds/Web-Quellen/Ausgeschlossen-Labels.
- components.js: source-excluded-badge.
- Chat-Widget: Title, alle 5 Buttons mit title+aria, Input-Placeholder.
- Chat-Begruessung in chat.js auf T() umgestellt.
- 50+ neue i18n-Keys. Cache-Buster components.js + chat.js + app.js
  auf v=20260514e gebumpt.

src/static/i18n/de.json

@@ -201,5 +201,63 @@
   "source.type.rss_feed": "RSS-Feed",
   "source.type.telegram": "Telegram",
   "source.type.web": "Web-Quelle",
-  "modal.hint.sources_german_only": "Nur deutschsprachige Quellen (DE, AT, CH)"
+  "modal.hint.sources_german_only": "Nur deutschsprachige Quellen (DE, AT, CH)",
+  "export.sections": "Bereiche",
+  "export.section.summary": "Zusammenfassung",
+  "export.section.report": "Recherchebericht / Lagebild",
+  "export.section.factcheck": "Faktencheck",
+  "export.section.sources": "Quellen",
+  "export.format": "Format",
+  "export.format.pdf": "PDF",
+  "export.format.docx": "Word (DOCX)",
+  "export.submit": "Exportieren",
+  "sources_modal.title": "Quellenverwaltung",
+  "sources_modal.stats.rss": "RSS-Feeds",
+  "sources_modal.stats.web": "Web-Quellen",
+  "sources_modal.stats.telegram": "Telegram",
+  "sources_modal.stats.excluded": "Ausgeschlossen",
+  "sources_modal.stats.articles": "Artikel gesamt",
+  "sources_modal.filter.type": "Quellentyp filtern",
+  "sources_modal.filter.type_all": "Alle Typen",
+  "sources_modal.filter.category": "Kategorie filtern",
+  "sources_modal.filter.category_all": "Alle Kategorien",
+  "sources_modal.filter.political": "Politische Ausrichtung filtern",
+  "sources_modal.filter.political_all": "Alle Ausrichtungen",
+  "sources_modal.filter.mediatype": "Medientyp filtern",
+  "sources_modal.filter.mediatype_all": "Alle Medientypen",
+  "sources_modal.filter.reliability": "Glaubwürdigkeit filtern",
+  "sources_modal.filter.reliability_all": "Alle Glaubwürdigkeiten",
+  "sources_modal.filter.extern": "Externe Reputation filtern",
+  "sources_modal.filter.extern_all": "Externe Reputation: alle",
+  "sources_modal.filter.alignment": "Geopolitische Nähe filtern",
+  "sources_modal.filter.alignment_all": "Alle Nähen",
+  "sources_modal.search": "Quellen durchsuchen",
+  "sources_modal.search_placeholder": "Suche...",
+  "sources_modal.add_source": "+ Quelle",
+  "sources_modal.form.url_label": "URL oder Domain",
+  "sources_modal.form.url_placeholder": "z.B. netzpolitik.org oder t.me/kanalname",
+  "sources_modal.form.discover": "Erkennen",
+  "sources_modal.form.name_placeholder": "Wird erkannt...",
+  "sources_modal.form.category": "Kategorie",
+  "sources_modal.form.type": "Typ",
+  "sources_modal.form.rss_url": "RSS-Feed URL",
+  "sources_modal.form.domain": "Domain",
+  "sources_modal.form.notes": "Notizen",
+  "sources_modal.form.notes_placeholder": "Optional",
+  "sources_modal.list.loading": "Lade Quellen...",
+  "sources_modal.excluded_badge": "Ausgeschlossen",
+  "chat.title": "AegisSight Assistent",
+  "chat.toggle_title": "Chat-Assistent",
+  "chat.toggle_aria": "Chat-Assistent öffnen",
+  "chat.new_title": "Neuer Chat",
+  "chat.new_aria": "Neuen Chat starten",
+  "chat.fullscreen_title": "Vollbild",
+  "chat.fullscreen_aria": "Vollbild umschalten",
+  "chat.close_title": "Schließen",
+  "chat.close_aria": "Chat schließen",
+  "chat.input_placeholder": "Frage stellen...",
+  "chat.send_title": "Senden",
+  "chat.send_aria": "Nachricht senden",
+  "chat.greeting": "Hallo! Ich bin der AegisSight Assistent. Stell mir gerne jede Frage rund um die Bedienung des Monitors, ich helfe dir weiter.",
+  "stats.articles_total": "Artikel gesamt"
 }