feat: Tutorial-Fortschritt serverseitig persistieren (Resume/Restart)

- Neuer Router /api/tutorial mit GET/PUT/DELETE für Fortschritt pro User
- DB-Migration: tutorial_step + tutorial_completed in users-Tabelle
- Resume-Dialog bei abgebrochenem Tutorial (Fortsetzen/Neu starten)
- Chat-Hinweis passt sich dem Tutorial-Status dynamisch an
- API-Methoden: getTutorialState, saveTutorialState, resetTutorialState

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/routers/tutorial.py

@@ -0,0 +1,77 @@
+"""Tutorial-Router: Fortschritt serverseitig pro User speichern."""
+import logging
+from fastapi import APIRouter, Depends
+from auth import get_current_user
+from database import db_dependency
+import aiosqlite
+
+logger = logging.getLogger("osint.tutorial")
+
+router = APIRouter(prefix="/api/tutorial", tags=["tutorial"])
+
+
+@router.get("/state")
+async def get_tutorial_state(
+    current_user: dict = Depends(get_current_user),
+    db: aiosqlite.Connection = Depends(db_dependency),
+):
+    """Tutorial-Fortschritt des aktuellen Nutzers abrufen."""
+    cursor = await db.execute(
+        "SELECT tutorial_step, tutorial_completed FROM users WHERE id = ?",
+        (current_user["id"],),
+    )
+    row = await cursor.fetchone()
+    if not row:
+        return {"current_step": None, "completed": False}
+    return {
+        "current_step": row["tutorial_step"],
+        "completed": bool(row["tutorial_completed"]),
+    }
+
+
+@router.put("/state")
+async def save_tutorial_state(
+    body: dict,
+    current_user: dict = Depends(get_current_user),
+    db: aiosqlite.Connection = Depends(db_dependency),
+):
+    """Tutorial-Fortschritt speichern (current_step und/oder completed)."""
+    updates = []
+    params = []
+
+    if "current_step" in body:
+        step = body["current_step"]
+        if step is not None and (not isinstance(step, int) or step < 0 or step > 31):
+            from fastapi import HTTPException
+            raise HTTPException(status_code=422, detail="current_step muss 0-31 oder null sein")
+        updates.append("tutorial_step = ?")
+        params.append(step)
+
+    if "completed" in body:
+        updates.append("tutorial_completed = ?")
+        params.append(1 if body["completed"] else 0)
+
+    if not updates:
+        return {"ok": True}
+
+    params.append(current_user["id"])
+    await db.execute(
+        f"UPDATE users SET {', '.join(updates)} WHERE id = ?",
+        params,
+    )
+    await db.commit()
+    return {"ok": True}
+
+
+@router.delete("/state")
+async def reset_tutorial_state(
+    current_user: dict = Depends(get_current_user),
+    db: aiosqlite.Connection = Depends(db_dependency),
+):
+    """Tutorial-Fortschritt zuruecksetzen (fuer Neustart)."""
+    await db.execute(
+        "UPDATE users SET tutorial_step = NULL, tutorial_completed = 0 WHERE id = ?",
+        (current_user["id"],),
+    )
+    await db.commit()
+    return {"ok": True}