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/nl.json

@@ -2176,7 +2176,12 @@
       "Italiano": "Italiaans",
       "Chinois": "Chinees",
       "Japonais": "Japans"
-    }
+    },
+    "exportMarkdown": "Exporteren als Markdown",
+    "importMarkdown": "Markdown importeren",
+    "markdownExportSuccess": "Notitie geëxporteerd als Markdown",
+    "markdownExportError": "Exporteren van notitie mislukt",
+    "markdownImportSuccess": "Markdown succesvol geïmporteerd"
   },
   "brainstorm": {
     "title": "Waves of Thought",
@@ -2306,7 +2311,16 @@
     "ownerBadge": "Owner",
     "waveBadge": "Wave {wave}",
     "quotaGuest": "De sessiehost heeft zijn AI-limiet bereikt. Vraag om een upgrade van het abonnement.",
-    "quotaHost": "Je hebt je AI-limiet voor deze brainstorm bereikt. Upgrade je abonnement om door te gaan."
+    "quotaHost": "Je hebt je AI-limiet voor deze brainstorm bereikt. Upgrade je abonnement om door te gaan.",
+    "downloadPptx": "PPTX",
+    "downloadPptxDesc": "Downloaden als PowerPoint",
+    "pptxSuccess": "PPTX gedownload",
+    "pptxError": "PPTX-export mislukt",
+    "fitToScreen": "Hercentreren",
+    "legendWave1": "Variaties",
+    "legendWave2": "Analogieën",
+    "legendWave3": "Verstoringen",
+    "legendConverted": "Geconverteerd"
   },
   "usageMeter": {
     "packName": "AI Discovery Pack",
@@ -2762,5 +2776,96 @@
     "uploadError": "Uploadfout",
     "uploadFailed": "Upload mislukt",
     "uploading": "Uploaden..."
+  },
+  "onboarding": {
+    "welcome_title": "Uw AI-versterkt geheugen",
+    "welcome_subtitle": "Momento onthoudt wat u vergeet.",
+    "welcome_cta": "Beginnen",
+    "skip": "Overslaan",
+    "step_notes_title": "Uw notities",
+    "step_notes_empty": "U heeft nog geen notities. Importeer uw eigen of begin met voorbeelden.",
+    "step_notes_import": "Mijn notities importeren",
+    "step_notes_demo": "5 voorbeeldnotities maken",
+    "step_notes_has_notes": "U heeft al {count} notities. Laten we de magie ontdekken.",
+    "step_notes_cta": "Mijn notities zijn klaar",
+    "step_aha_title": "Vind wat u vergeten bent",
+    "step_aha_subtitle": "Stel een vraag. Vind een vergeten notitie.",
+    "step_aha_placeholder": "notities over productiviteit...",
+    "step_aha_cta": "Momento verkennen",
+    "progress": "{current} van {total}",
+    "creating_demo_notes": "Voorbeeldnotities aanmaken...",
+    "demo_notes_ready": "5 voorbeeldnotities aangemaakt!",
+    "badge_credits": "⚡ Nog {count} credits",
+    "badge_upgrade": "Upgraden naar Pro →",
+    "no_results": "Geen resultaten — probeer een andere zoekopdracht.",
+    "search_credit_used": "1 zoekopdracht gebruikt",
+    "quota_exceeded": "Zoeklimiet bereikt — upgrade naar Pro.",
+    "step_aha_search_button": "Zoeken",
+    "step_aha_search_aria": "Zoek in je notities",
+    "step_notes_hint": "💡 Deze notities voeden de AI-zoekdemo in de volgende stap.",
+    "step_features_title": "Uw AI-superkrachten",
+    "step_features_subtitle": "Kies waar u wilt beginnen.",
+    "step_features_cta": "Aan de slag!",
+    "feature_search_title": "Semantisch zoeken",
+    "feature_search_desc": "Vind elke notitie op betekenis, niet alleen op trefwoorden.",
+    "feature_flashcards_title": "AI-flashcards",
+    "feature_flashcards_desc": "Genereer SRS-revisiekaarten uit uw notities met één klik.",
+    "feature_brainstorm_title": "AI-brainstormen",
+    "feature_brainstorm_desc": "AI-gestuurde collaboratieve brainstormsessies.",
+    "feature_chat_title": "Chat met uw notities",
+    "feature_chat_desc": "Stel vragen aan uw persoonlijke kennisbank.",
+    "feature_insights_title": "Semantische inzichten",
+    "feature_insights_desc": "Ontdek verborgen verbanden tussen uw ideeën.",
+    "feature_export_title": "Markdown-export",
+    "feature_export_desc": "Importeer en exporteer uw notities in Markdown-formaat.",
+    "welcome_title_name": "Hallo {name} 👋",
+    "import_formats": "Geaccepteerde formaten: .md, .txt",
+    "import_error": "Sommige bestanden konden niet worden geïmporteerd.",
+    "import_notes_ready": "{count} notitie(s) geïmporteerd!",
+    "action_write_title": "Schrijf uw eerste echte notitie",
+    "action_write_desc": "Maak een notitie en leg uw ideeën vast.",
+    "action_flashcards_title": "Maak uw eerste flashcards",
+    "action_flashcards_desc": "Open een notitie en klik op de flashcards-knop.",
+    "action_brainstorm_title": "Start een AI-brainstorm",
+    "action_brainstorm_desc": "Verken uw ideeën met een AI-agent.",
+    "action_try": "Proberen",
+    "step_features_cta_all": "Alles klaar — aan de slag!",
+    "action_write_where": "Sluit → klik op \"+ Nieuwe notitie\" in de zijbalk",
+    "action_flashcards_where": "Sluit → open een notitie → 🃏-knop in de werkbalk",
+    "action_brainstorm_where": "Sluit → \"Canvas\"-sectie in de zijbalk",
+    "pill_resume": "✨ Tour hervatten",
+    "action_done": "Geprobeerd!",
+    "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."
   }
-}
+}