Backend: WAL+busy_timeout, DB↔Datei-Reconcile beim Start, zentraler JSON-Parser (jsonio)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/database.py

@@ -60,6 +60,9 @@ async def get_db() -> aiosqlite.Connection:
 
 async def init_db():
     db = await get_db()
+    # WAL übersteht Crashes deutlich besser; busy_timeout fängt kurze Locks ab.
+    await db.execute("PRAGMA journal_mode=WAL")
+    await db.execute("PRAGMA busy_timeout=5000")
     await db.execute(CREATE_GUIDES)
     await db.execute(CREATE_PROGRESS)
     await db.execute(CREATE_TOPICS)