fix: page not found → redirect workspaces (dashboard.py manquait)

app/routers/dashboard.py

@@ -287,7 +287,7 @@ async def view_page_root(request: Request, page_id: int):
     with get_conn() as conn:
         row = conn.execute("SELECT * FROM pages WHERE id=?", (page_id,)).fetchone()
         if not row:
-            return HTMLResponse("<h2>Page not found</h2>", status_code=404)
+            return RedirectResponse("/workspaces", status_code=302)
     page = dict(row)
 
     ws = page.get("workspace", "")