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/static/js/tutorial.js

@@ -12,6 +12,7 @@ const Tutorial = {
     _resizeHandler: null,
     _demoRunning: false,
     _lastExitedStep: -1,
+    _highestStep: -1,
     _stepTimers: [],      // setTimeout-IDs fuer den aktuellen Step
     _savedState: null,   // Dashboard-Zustand vor dem Tutorial
 
@@ -1152,14 +1153,52 @@ const Tutorial = {
     // -----------------------------------------------------------------------
     // Lifecycle
     // -----------------------------------------------------------------------
-    start() {
+    async start(forceRestart) {
         if (this._isActive) return;
-        this._isActive = true;
-        this._currentStep = -1;
 
-        // Chat schließen falls offen
+        // Chat schliessen falls offen
         if (typeof Chat !== 'undefined' && Chat._isOpen) Chat.close();
 
+        // Server-State laden (Fallback: direkt starten)
+        var state = null;
+        try { state = await API.getTutorialState(); } catch(e) {}
+
+        // Resume-Dialog wenn mittendrin abgebrochen
+        if (!forceRestart && state && !state.completed && state.current_step !== null && state.current_step > 0) {
+            this._showResumeDialog(state.current_step);
+            return;
+        }
+
+        this._startInternal(forceRestart ? 0 : null);
+    },
+
+    _showResumeDialog(step) {
+        var self = this;
+        var overlay = document.createElement('div');
+        overlay.className = 'tutorial-resume-overlay';
+        overlay.innerHTML = '<div class=tutorial-resume-dialog>'
+            + '<p>Sie haben den Rundgang bei <strong>Schritt ' + (step + 1) + '/' + this._steps.length + '</strong> unterbrochen.</p>'
+            + '<div class=tutorial-resume-actions>'
+            + '<button class=tutorial-btn tutorial-btn-next id=tutorial-resume-btn>Fortsetzen</button>'
+            + '<button class=tutorial-btn tutorial-btn-secondary id=tutorial-restart-btn>Neu starten</button>'
+            + '</div></div>';
+        document.body.appendChild(overlay);
+        document.getElementById('tutorial-resume-btn').addEventListener('click', function() {
+            overlay.remove();
+            self._startInternal(step);
+        });
+        document.getElementById('tutorial-restart-btn').addEventListener('click', async function() {
+            overlay.remove();
+            try { await API.resetTutorialState(); } catch(e) {}
+            self._startInternal(0);
+        });
+    },
+
+    _startInternal(resumeStep) {
+        this._isActive = true;
+        this._highestStep = -1;
+        this._currentStep = -1;
+
         // Overlay einblenden + Klicks blockieren
         this._els.overlay.classList.add('active');
         document.body.classList.add('tutorial-active');
@@ -1172,7 +1211,11 @@ const Tutorial = {
         this._resizeHandler = this._onResize.bind(this);
         window.addEventListener('resize', this._resizeHandler);
 
-        this.next();
+        if (resumeStep && resumeStep > 0) {
+            this.goToStep(resumeStep);
+        } else {
+            this.next();
+        }
     },
 
     stop() {
@@ -1230,7 +1273,14 @@ const Tutorial = {
             this._resizeHandler = null;
         }
 
-        this._markSeen();
+        // Fortschritt serverseitig speichern
+        if (this._lastExitedStep >= 0 && this._lastExitedStep < this._steps.length - 1) {
+            // Mittendrin abgebrochen — Schritt speichern
+            API.saveTutorialState({ current_step: this._lastExitedStep }).catch(function() {});
+        } else {
+            // Komplett durchlaufen oder letzter Schritt
+            this._markSeen();
+        }
     },
 
     // -----------------------------------------------------------------------
@@ -1258,6 +1308,7 @@ const Tutorial = {
 
         if (this._currentStep >= 0) this._exitStep(this._currentStep);
         this._currentStep = index;
+        if (index > this._highestStep) this._highestStep = index;
         this._enterStep(index);
     },
 
@@ -2231,6 +2282,7 @@ const Tutorial = {
     // -----------------------------------------------------------------------
     _markSeen() {
         try { localStorage.setItem('osint_tutorial_seen', '1'); } catch(e) {}
+        API.saveTutorialState({ completed: true, current_step: null }).catch(function() {});
     },
 
     _hasSeen() {