feat(settings): organization_settings KV-Tabelle + org_settings Helper

Neue Tabelle organization_settings (organization_id, key, value) als KV-Store
fuer Org-spezifische Konfiguration. Erster Use-Case: output_language (de|en).
Bestandsorgs werden per Migration auf de gesetzt.

Helper services/org_settings.py mit get_org_setting / set_org_setting /
get_org_language / language_display. In-Memory-Cache TTL 60s.

Phase 1 von 8 (eng_demo / Org-Sprache).

src/database.py

@@ -345,6 +345,15 @@ CREATE TABLE IF NOT EXISTS network_generation_log (
     error_message TEXT,
     tenant_id INTEGER REFERENCES organizations(id)
 );
+
+CREATE TABLE IF NOT EXISTS organization_settings (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    organization_id INTEGER NOT NULL REFERENCES organizations(id) ON DELETE CASCADE,
+    key TEXT NOT NULL,
+    value TEXT,
+    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    UNIQUE(organization_id, key)
+);
 """
 
 
@@ -782,6 +791,32 @@ async def init_db():
             await db.commit()
             logger.info("Migration: token_usage_monthly Tabelle erstellt")
 
+        # Migration: organization_settings KV-Tabelle (pro Org Sprache, ggf. spaeter weitere Settings)
+        cursor = await db.execute("SELECT name FROM sqlite_master WHERE type='table' AND name='organization_settings'")
+        if not await cursor.fetchone():
+            await db.execute("""
+                CREATE TABLE organization_settings (
+                    id INTEGER PRIMARY KEY AUTOINCREMENT,
+                    organization_id INTEGER NOT NULL REFERENCES organizations(id) ON DELETE CASCADE,
+                    key TEXT NOT NULL,
+                    value TEXT,
+                    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+                    UNIQUE(organization_id, key)
+                )
+            """)
+            await db.commit()
+            logger.info("Migration: organization_settings Tabelle erstellt")
+
+        # Default-Setting output_language='de' fuer Orgs ohne Eintrag
+        await db.execute("""
+            INSERT OR IGNORE INTO organization_settings (organization_id, key, value)
+            SELECT id, 'output_language', 'de' FROM organizations
+            WHERE id NOT IN (
+                SELECT organization_id FROM organization_settings WHERE key='output_language'
+            )
+        """)
+        await db.commit()
+
     # Verwaiste running-Eintraege beim Start als error markieren (aelter als 15 Min)
         await db.execute(
             """UPDATE refresh_log SET status = 'error', error_message = 'Verwaist beim Neustart',