Epic 6: Stories 6-2 (Markdown roundtrip) + 6-3 (Brainstorm PPTX + Canvas)

Story 6-2 — Markdown roundtrip export/import:
- lib/editor/markdown-export.ts: tiptapHTMLToMarkdown, markdownToHTML, looksLikeMarkdown
- lib/editor/markdown-paste-extension.ts: TipTap extension paste Markdown → blocs
- note-editor-toolbar.tsx: export .md + import .md (file picker)
- rich-text-editor.tsx: intégration MarkdownPasteExtension
- 40 tests unitaires markdown-export.test.ts

Story 6-3 — Brainstorm PPTX + Canvas:
- lib/brainstorm/export-pptx.ts: génération PPTX 5 slides (pptxgenjs)
- app/api/brainstorm/[sessionId]/export-pptx/route.ts: route POST protégée
- brainstorm-page.tsx: bouton PPTX, auto-select session, fix emoji, fix router.replace
- wave-canvas.tsx: fitTrigger recentrage, légende bas-droite

Onboarding activation wizard (Story 6-1):
- components/onboarding/: wizard multi-étapes, hints éditeur
- app/api/onboarding/: route PATCH onboarding
- prisma/migrations: champs onboarding user

Locales: 15 langues mises à jour (brainstorm, markdown, onboarding keys)
Sprint: 6-1 done, 6-2 review, 6-3 review

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

memento-note/locales/de.json

@@ -2176,7 +2176,12 @@
       "Italiano": "Italienisch",
       "Chinois": "Chinesisch",
       "Japonais": "Japanisch"
-    }
+    },
+    "exportMarkdown": "Als Markdown exportieren",
+    "importMarkdown": "Markdown importieren",
+    "markdownExportSuccess": "Notiz als Markdown exportiert",
+    "markdownExportError": "Export der Notiz fehlgeschlagen",
+    "markdownImportSuccess": "Markdown erfolgreich importiert"
   },
   "brainstorm": {
     "title": "Waves of Thought",
@@ -2306,7 +2311,16 @@
     "ownerBadge": "Owner",
     "waveBadge": "Wave {wave}",
     "quotaGuest": "Der Gastgeber der Sitzung hat sein KI-Kontingent aufgebraucht. Bitte ihn, seinen Tarif zu erweitern.",
-    "quotaHost": "Sie haben Ihr KI-Kontingent für dieses Brainstorming erreicht. Wechseln Sie den Tarif, um fortzufahren."
+    "quotaHost": "Sie haben Ihr KI-Kontingent für dieses Brainstorming erreicht. Wechseln Sie den Tarif, um fortzufahren.",
+    "downloadPptx": "PPTX",
+    "downloadPptxDesc": "Als PowerPoint herunterladen",
+    "pptxSuccess": "PPTX heruntergeladen",
+    "pptxError": "PPTX-Export fehlgeschlagen",
+    "fitToScreen": "Zentrieren",
+    "legendWave1": "Variationen",
+    "legendWave2": "Analogien",
+    "legendWave3": "Unterbrechungen",
+    "legendConverted": "Konvertiert"
   },
   "usageMeter": {
     "packName": "AI Discovery Pack",
@@ -2762,5 +2776,96 @@
     "uploadError": "Upload-Fehler",
     "uploadFailed": "Upload fehlgeschlagen",
     "uploading": "Wird hochgeladen..."
+  },
+  "onboarding": {
+    "welcome_title": "Ihr KI-erweitertes Gedächtnis",
+    "welcome_subtitle": "Momento erinnert sich an das, was Sie vergessen.",
+    "welcome_cta": "Loslegen",
+    "skip": "Überspringen",
+    "step_notes_title": "Ihre Notizen",
+    "step_notes_empty": "Sie haben noch keine Notizen. Importieren Sie Ihre oder beginnen Sie mit Beispielen.",
+    "step_notes_import": "Notizen importieren",
+    "step_notes_demo": "5 Beispielnotizen erstellen",
+    "step_notes_has_notes": "Sie haben bereits {count} Notizen. Entdecken wir die Magie.",
+    "step_notes_cta": "Meine Notizen sind bereit",
+    "step_aha_title": "Finden Sie, was Sie vergessen haben",
+    "step_aha_subtitle": "Stellen Sie eine Frage. Finden Sie eine vergessene Notiz.",
+    "step_aha_placeholder": "Notizen zur Produktivität...",
+    "step_aha_cta": "Momento erkunden",
+    "progress": "{current} von {total}",
+    "creating_demo_notes": "Beispielnotizen werden erstellt...",
+    "demo_notes_ready": "5 Beispielnotizen erstellt!",
+    "badge_credits": "⚡ Noch {count} Credits",
+    "badge_upgrade": "Auf Pro upgraden →",
+    "no_results": "Keine Ergebnisse — andere Anfrage versuchen.",
+    "search_credit_used": "1 Suche verwendet",
+    "quota_exceeded": "Suchlimit erreicht — auf Pro upgraden für unbegrenzte Suchen.",
+    "step_aha_search_button": "Suchen",
+    "step_aha_search_aria": "Notizen durchsuchen",
+    "step_notes_hint": "💡 Diese Notizen ermöglichen die KI-Suchdemo im nächsten Schritt.",
+    "step_features_title": "Ihre KI-Superkräfte",
+    "step_features_subtitle": "Wählen Sie Ihren Einstieg.",
+    "step_features_cta": "Los geht's!",
+    "feature_search_title": "Semantische Suche",
+    "feature_search_desc": "Finden Sie jede Notiz nach Bedeutung, nicht nur nach Schlüsselwörtern.",
+    "feature_flashcards_title": "KI-Karteikarten",
+    "feature_flashcards_desc": "SRS-Lernkarten aus Ihren Notizen in einem Klick erstellen.",
+    "feature_brainstorm_title": "KI-Brainstorming",
+    "feature_brainstorm_desc": "KI-gestützte kollaborative Brainstorming-Sitzungen.",
+    "feature_chat_title": "Mit Ihren Notizen chatten",
+    "feature_chat_desc": "Stellen Sie Ihrer persönlichen Wissensdatenbank Fragen.",
+    "feature_insights_title": "Semantische Einblicke",
+    "feature_insights_desc": "Entdecken Sie versteckte Verbindungen zwischen Ihren Ideen.",
+    "feature_export_title": "Markdown-Export",
+    "feature_export_desc": "Importieren und exportieren Sie Ihre Notizen im Markdown-Format.",
+    "welcome_title_name": "Hallo {name} 👋",
+    "import_formats": "Akzeptierte Formate: .md, .txt",
+    "import_error": "Einige Dateien konnten nicht importiert werden. Bitte erneut versuchen.",
+    "import_notes_ready": "{count} Notiz(en) importiert!",
+    "action_write_title": "Ihre erste echte Notiz schreiben",
+    "action_write_desc": "Erstellen Sie eine Notiz und beginnen Sie Ideen festzuhalten.",
+    "action_flashcards_title": "Erste Karteikarten erstellen",
+    "action_flashcards_desc": "Öffnen Sie eine Notiz und klicken Sie auf Karteikarten.",
+    "action_brainstorm_title": "KI-Brainstorming starten",
+    "action_brainstorm_desc": "Erkunden Sie Ihre Ideen mit einem KI-Agenten.",
+    "action_try": "Ausprobieren",
+    "step_features_cta_all": "Alles bereit — los geht's!",
+    "action_write_where": "Schließen → \"+ Neue Notiz\" in der Seitenleiste klicken",
+    "action_flashcards_where": "Schließen → Notiz öffnen → 🃏-Button in der Toolbar",
+    "action_brainstorm_where": "Schließen → \"Canvas\"-Bereich in der Seitenleiste",
+    "pill_resume": "✨ Tour fortsetzen",
+    "action_done": "Getestet!",
+    "editor_hints_title": "Editor tips",
+    "editor_hints_got_it": "Got it!",
+    "hint_slash_title": "\"/\" command — insert blocks",
+    "hint_slash_desc": "In the editor, type \"/\" to open the block menu: heading, list, code block, table, to-do list, and AI commands (Clarify, Shorten, Improve, Expand).",
+    "hint_ai_title": "Built-in AI assistant",
+    "hint_ai_desc": "Click the ✨ button in the toolbar to open the AI panel — ask questions, summarize, rewrite, or brainstorm directly in your note.",
+    "hint_version_title": "Version history",
+    "hint_version_desc": "Click the ⓘ button in the toolbar → \"Versions\" tab. Enable versioning, then save and restore snapshots of your note at any time.",
+    "hint_flashcards_title": "Generate flashcards",
+    "hint_flashcards_desc": "Click the 🎓 button in the toolbar to auto-generate flashcards from your note for spaced repetition review.",
+    "hint_links_title": "Links between notes",
+    "hint_links_desc": "Type \"[[\" in the editor to search and link to another note. Linked notes appear as backlinks at the bottom of the note.",
+    "hint_create_note_title": "Create a note",
+    "hint_create_note_desc": "Click the \"+\" button in the sidebar or press Ctrl+N to create a new note. Then start writing.",
+    "hint_flip_title": "Flip the card",
+    "hint_flip_desc": "Press Space (or click the card) to flip it and reveal the answer.",
+    "hint_rate_keys_title": "Rate with keyboard",
+    "hint_rate_keys_desc": "After flipping, press 1 (Hard), 2 (Difficult), 3 (Good) or 4 (Easy) to rate the card. The SM-2 algorithm schedules your next review automatically.",
+    "hint_generate_from_note_title": "Generate from a note",
+    "hint_generate_from_note_desc": "Open any note and click the 🎓 button in the toolbar to automatically generate flashcards from its content.",
+    "hint_brainstorm_start_title": "Start with an idea",
+    "hint_brainstorm_start_desc": "Type any concept or question in the input field and press Enter. The AI will generate a set of ideas around it.",
+    "hint_brainstorm_deepen_title": "Deepen an idea",
+    "hint_brainstorm_deepen_desc": "Click on any idea card to expand it with sub-ideas and explore it further.",
+    "hint_brainstorm_export_title": "Export your session",
+    "hint_brainstorm_export_desc": "When done, export the entire brainstorm session as a structured note saved to your notebook.",
+    "hint_insights_clusters_title": "Note clusters",
+    "hint_insights_clusters_desc": "Your notes are automatically grouped into thematic clusters. Click a cluster to explore the notes it contains.",
+    "hint_insights_bridge_title": "Bridge notes",
+    "hint_insights_bridge_desc": "Bridge notes connect multiple clusters. They are highlighted because they hold your knowledge graph together.",
+    "hint_insights_refresh_title": "Refresh clusters",
+    "hint_insights_refresh_desc": "If you've added new notes, click the refresh button to recalculate the clusters with the latest content."
   }
-}
+}