feat: guide d'utilisation - couverture complete, telechargement MD/PDF, section Architecture Mermaid, guide desktop elargi (#105, BUG-067)

backend/main.py

@@ -1747,6 +1747,37 @@ def _safe_export_name(name: str) -> str:
     return cleaned or "document"
 
 
+@app.get(
+    "/api/guide/download",
+    response_class=Response,
+    responses={200: {"content": {"application/pdf": {}, "text/markdown": {}}}},
+)
+async def api_guide_download(
+    format: str = Query("md", description="Download format: 'md' or 'pdf'"),
+    lang: str = Query("fr", description="Guide language: 'fr' or 'en'"),
+    current_user=Depends(require_auth),
+):
+    """Download the in-app user guide as Markdown or PDF (#105).
+
+    The document is generated from the live help modal in index.html resolved
+    through the locale files, so it always mirrors exactly what the user sees.
+    """
+    from backend.guide_export import get_guide_document
+
+    if format not in ("md", "pdf"):
+        raise HTTPException(status_code=400, detail="format doit être 'md' ou 'pdf'")
+    try:
+        payload, media, fname = get_guide_document(format, lang)
+    except Exception as e:  # weasyprint/reportlab unavailable
+        logger.exception("guide export failed")
+        raise HTTPException(status_code=500, detail=f"Export impossible: {e}") from e
+    return Response(
+        content=payload,
+        media_type=media,
+        headers={"Content-Disposition": f'attachment; filename="{fname}"'},
+    )
+
+
 @app.put("/api/file/{vault_name}/save", response_model=FileSaveResponse)
 async def api_file_save(
     vault_name: str,