fix: add Cache-Control: no-store to prevent stale JS in browser cache

Both board.py and dashboard.py page endpoints now return
Cache-Control: no-store, max-age=0 headers to prevent the browser
from caching the page HTML with broken x-data attributes.

app/routers/board.py

@@ -754,7 +754,8 @@ async def view_page(request: Request, page_id: int):
            "page_share_mode": page.get("share_mode", "private"),
            "page_published": bool(page.get("published", 0))}
     template = env.get_template("page_editor.html")
-    return template.render(**ctx)
+    response = template.render(**ctx)
+    return HTMLResponse(content=response, headers={"Cache-Control": "no-store, max-age=0"})
 
 @router.post("/api/sync/{owner}/{repo}")
 async def sync_project(owner: str, repo: str):

app/routers/dashboard.py

@@ -171,7 +171,8 @@ async def view_page_root(request: Request, page_id: int):
            "page_share_mode": page.get("share_mode", "private"),
            "page_published": bool(page.get("published", 0))}
     template = env.get_template("page_editor.html")
-    return template.render(**ctx)
+    response = template.render(**ctx)
+    return HTMLResponse(content=response, headers={"Cache-Control": "no-store, max-age=0"})
 
 
 @router.get("/accounts", response_class=HTMLResponse)