feat(frontend): Light-i18n + Org-Sprache durch /auth/me

Backend:
- UserMeResponse um output_language (de | en) erweitert.
- /auth/me liefert die Org-Sprache aus organization_settings.

Frontend:
- Neu: static/js/i18n.js mit T(key)-Helper, I18N.load(lang) und
  applyDom() ueber data-i18n + data-i18n-attr.
- Neu: static/i18n/de.json + en.json (sichtbare Bereiche: Sidebar,
  Header, Modal-Titel, Faktencheck-Status, Refresh-Hinweise).
- dashboard.html: i18n.js Script-Tag vor api.js, data-i18n auf den
  prominenten Strings (Abmelden, + Neuer Fall, Alle/Eigene, Sidebar-
  Sektionen, Bericht exportieren, Faktencheck-Tab, Lage anlegen).
  Tutorial.init() entfernt aus DOMContentLoaded.
- components.js: factCheckLabels/Tooltips/ChipLabels als Getter ueber
  T() mit DE-Fallbacks.
- app.js: vor Setup wird I18N.load(user.output_language) aufgerufen und
  applyDom() ausgefuehrt. Tutorial.init() laeuft nur bei lang === de.

Phase 6 von 8 (eng_demo / Org-Sprache).

src/static/i18n/en.json

@@ -0,0 +1,64 @@
+{
+  "sidebar.live_monitoring": "Live monitoring",
+  "sidebar.research": "Research",
+  "sidebar.empty": "No situations yet",
+  "header.logout": "Sign out",
+  "header.new_incident": "+ New situation",
+  "header.theme_toggle": "Toggle theme",
+  "header.notifications": "Notifications",
+  "filter.all": "All",
+  "filter.own": "Own",
+  "filter.everything": "Everything",
+  "common.close": "Close",
+  "common.cancel": "Cancel",
+  "common.save": "Save",
+  "common.delete": "Delete",
+  "common.edit": "Edit",
+  "common.loading": "Loading...",
+  "common.confirm": "Confirm",
+  "common.error": "Error",
+  "modal.new_incident.title": "Create new situation",
+  "modal.new_incident.title_field": "Incident title",
+  "modal.new_incident.description": "Description / context",
+  "modal.new_incident.enhance": "Generate description",
+  "modal.new_incident.visibility": "Visibility",
+  "modal.new_incident.visibility_public": "Public",
+  "modal.new_incident.visibility_private": "Private",
+  "modal.new_incident.submit": "Create situation",
+  "modal.sources.title": "Source management",
+  "modal.sources.approve_all_high": "Approve all ≥ 0.85",
+  "modal.export.title": "Export report",
+  "modal.fc_status.title": "Fact-check status change",
+  "tile.factcheck": "Fact check",
+  "tile.research_evaluated": "Research situations are evaluated multiple times...",
+  "tile.summary": "Briefing",
+  "tile.summary_research": "Research report",
+  "tile.timeline": "Timeline",
+  "tile.map": "Map",
+  "tile.sources": "Sources",
+  "fc.label.confirmed": "Confirmed by multiple sources",
+  "fc.label.unconfirmed": "Not independently confirmed",
+  "fc.label.contradicted": "Contradicted",
+  "fc.label.developing": "Facts still developing",
+  "fc.label.established": "Established fact (3+ sources)",
+  "fc.label.disputed": "Disputed matter",
+  "fc.label.unverified": "Not independently verifiable",
+  "fc.tooltip.confirmed": "Confirmed: at least two independent, reputable sources support this claim consistently.",
+  "fc.tooltip.established": "Established: three or more independent sources confirm the matter. High reliability.",
+  "fc.tooltip.developing": "Developing: the facts are still in flux. New information may change the picture.",
+  "fc.tooltip.unconfirmed": "Unconfirmed: known from only one source so far. Independent confirmation is pending.",
+  "fc.tooltip.unverified": "Unverified: the claim could not yet be checked against available sources.",
+  "fc.tooltip.disputed": "Disputed: sources disagree. There is both supporting and contradicting evidence.",
+  "fc.tooltip.contradicted": "Contradicted: reliable sources contradict this claim. Likely false.",
+  "fc.chip.confirmed": "Confirmed",
+  "fc.chip.unconfirmed": "Unconfirmed",
+  "fc.chip.contradicted": "Contradicted",
+  "fc.chip.developing": "Developing",
+  "fc.chip.established": "Established",
+  "fc.chip.disputed": "Disputed",
+  "fc.chip.unverified": "Unverified",
+  "refresh.no_developments": "No new developments",
+  "refresh.new_articles_suffix": "new articles",
+  "refresh.confirmed_suffix": "facts confirmed",
+  "refresh.contradicted_suffix": "contradicted"
+}