完善会话草稿恢复与附件保留，统一人工服务时区

static/css/theme.css

@@ -81,6 +81,7 @@ svg { display: block; flex-shrink: 0; }
 .emoji-picker { position: absolute; bottom: calc(100% + 12px); left: 0; z-index: 20; display: grid; grid-template-columns: repeat(5, 1fr); width: 230px; padding: 10px; border: 1px solid var(--border); border-radius: 10px; background: var(--surface); box-shadow: var(--shadow); }
 .emoji-picker button { border: 0; border-radius: 6px; background: transparent; font-size: 22px; padding: 6px; }
 .emoji-picker button:hover { background: var(--surface-hover); }
+.attachment-unavailable { display: block; max-width: 260px; padding: 12px; border: 1px dashed var(--border); border-radius: 8px; background: var(--surface-soft); color: var(--secondary); font-size: 12px; line-height: 1.6; }
 .sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; }
 .empty-caption { color: var(--muted); font-size: 12px; line-height: 1.8; }
 ::-webkit-scrollbar { width: 5px; height: 5px; }