feat(sources): externer Reputations-Layer (IFCN + EUvsDisinfo)

Externe Datenquellen (kostenlos, Open Data) ergaenzen die LLM-geschaetzte
Reliability-Achse mit objektiven Signalen:

- IFCN-Signatories (raw.githubusercontent.com/IFCN/verified-signatories):
  Plain-Text-Liste anerkannter Faktencheck-Organisationen.
- EUvsDisinfo (Zenodo CSV): Pro-Kreml-Desinformations-Datenbank.

Schema-Erweiterung:
- ifcn_signatory, eu_disinfo_listed, eu_disinfo_case_count,
  eu_disinfo_last_seen, external_data_synced_at.

Service src/services/external_reputation.py:
- sync_ifcn_signatories(), sync_eu_disinfo(), apply_reputation_overrides(),
  sync_all() mit Domain-Normalisierung (lowercase, ohne www., ohne Schema).

Reliability-Override-Regeln (laufen nach Approve und manuellem Sync):
- ifcn_signatory=1 -> reliability=sehr_hoch
- eu_disinfo_case_count >= 5 -> reliability=sehr_niedrig
- eu_disinfo_case_count >= 1 -> Reliability eine Stufe runter (max niedrig)

API: POST /api/sources/external-reputation/sync (Admin, BackgroundTask).
Filter: ?ifcn_signatory=true, ?eu_disinfo_listed=true.

UI:
- Filter-Dropdown "Externe Reputation" im Quellen-Modal.
- Badges: gruenes "IFCN" und rotes "EU-Desinfo (n)".
- Tooltip macht Reliability-Quelle transparent: "(IFCN-Faktenchecker)",
  "(EU-Desinfo, n Faelle)" oder "(LLM-Schaetzung)".
- "Externe Daten syncen"-Button im Review-Toolbar (Admin-only).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/database.py

@@ -176,7 +176,12 @@ CREATE TABLE IF NOT EXISTS sources (
     proposed_alignments_json TEXT,
     proposed_confidence REAL,
     proposed_reasoning TEXT,
-    proposed_at TIMESTAMP
+    proposed_at TIMESTAMP,
+    eu_disinfo_listed INTEGER DEFAULT 0,
+    eu_disinfo_case_count INTEGER DEFAULT 0,
+    eu_disinfo_last_seen TIMESTAMP,
+    ifcn_signatory INTEGER DEFAULT 0,
+    external_data_synced_at TIMESTAMP
 );
 
 CREATE TABLE IF NOT EXISTS source_alignments (
@@ -668,6 +673,20 @@ async def init_db():
         if any(c not in src_columns for c in ("political_orientation", "media_type", "reliability")):
             logger.info("Migration: Klassifikations-Spalten zu sources hinzugefuegt")
 
+        # Migration: externe Reputations-Daten (EUvsDisinfo + IFCN)
+        for col, ddl in [
+            ("eu_disinfo_listed", "ALTER TABLE sources ADD COLUMN eu_disinfo_listed INTEGER DEFAULT 0"),
+            ("eu_disinfo_case_count", "ALTER TABLE sources ADD COLUMN eu_disinfo_case_count INTEGER DEFAULT 0"),
+            ("eu_disinfo_last_seen", "ALTER TABLE sources ADD COLUMN eu_disinfo_last_seen TIMESTAMP"),
+            ("ifcn_signatory", "ALTER TABLE sources ADD COLUMN ifcn_signatory INTEGER DEFAULT 0"),
+            ("external_data_synced_at", "ALTER TABLE sources ADD COLUMN external_data_synced_at TIMESTAMP"),
+        ]:
+            if col not in src_columns:
+                await db.execute(ddl)
+                await db.commit()
+        if any(c not in src_columns for c in ("eu_disinfo_listed", "ifcn_signatory")):
+            logger.info("Migration: externe Reputations-Spalten zu sources hinzugefuegt")
+
         # Migration: source_alignments-Tabelle (Mehrfach-Tags fuer geopolitische Naehe)
         cursor = await db.execute(
             "SELECT name FROM sqlite_master WHERE type='table' AND name='source_alignments'"