feat(core): notification inbox infinite scroll + command palette fix (+ pending WIP)

消息中心:全量渲染 → 真·后端分页滚动加载
- backend(ops/views): NotificationPagination(10/页,page_size 可覆盖)+
  响应回 type_counts(按收件人绝对计数,不受分页/搜索影响)
- frontend(messages): 自管分页,滚到底加载下一批;tab/搜索走服务端并重置到第1页;
  代号作废在途旧请求防切换卡空白;乐观标已读;「已加载 X / Y」分母用当前筛选总数
- api/App/types: listNotifications 支持 page/page_size/search;allNotifications 携带 type_counts

命令面板(侧边栏搜索):修复点开后 UI 错位
- app-shell: 遮罩 className 漏了基类 shell-command-bg(只有 .show)致无定位塌到左下;
  补回基类 + header 类名对齐 .shell-command-h
- messages-page.css: 工作台收进视口高度,收件箱在面板内滚动

本次提交一并带入此前若干未提交 WIP(account/ai-tools/library/pipeline/products/settings +
accounts/ai/assets/billing/projects 后端),按用户要求整体推 dev。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

core/backend/apps/ai/services.py

@@ -1,7 +1,11 @@
 import re
+import subprocess
+import tempfile
 import uuid
 from datetime import timedelta
 from decimal import Decimal
+from io import BytesIO
+from pathlib import Path
 from django.db import transaction
 from django.utils import timezone
 
@@ -184,6 +188,34 @@ def generate_project_script(*, project, user, user_prompt: str, selling_point_id
         raise
 
 
+def _generate_video_poster(*, video_bytes: bytes, team, project, asset_id) -> "StoredObject | None":
+    """用 ffmpeg 抽视频首帧作为封面(poster)并上传 TOS。best-effort:任何失败都返回 None,不影响视频资产落地。"""
+    if not video_bytes:
+        return None
+    try:
+        with tempfile.TemporaryDirectory(prefix="airshelf-poster-") as tmp:
+            tmp_dir = Path(tmp)
+            video_path = tmp_dir / "in.mp4"
+            poster_path = tmp_dir / "poster.jpg"
+            video_path.write_bytes(video_bytes)
+            proc = subprocess.run(
+                ["ffmpeg", "-y", "-ss", "0", "-i", str(video_path), "-frames:v", "1", "-q:v", "3", str(poster_path)],
+                capture_output=True,
+                timeout=60,
+            )
+            if proc.returncode != 0 or not poster_path.exists():
+                return None
+            poster_bytes = poster_path.read_bytes()
+            if not poster_bytes:
+                return None
+            object_key = f"teams/{team.id}/projects/{project.id}/generated/{asset_id}-poster.jpg"
+            return TosStorage().upload_fileobj(
+                fileobj=BytesIO(poster_bytes), object_key=object_key, content_type="image/jpeg"
+            )
+    except Exception:  # noqa: BLE001 — poster 仅用于展示,失败不阻断
+        return None
+
+
 def _store_generated_media(*, team, user, project, task, media: str, name: str, category: str, asset_type: str) -> Asset:
     fileobj, content_type = VolcanoArkProvider.media_to_bytes(media)
     suffix = ".png"
@@ -214,6 +246,22 @@ def _store_generated_media(*, team, user, project, task, media: str, name: str,
         size_bytes=stored.size_bytes,
         is_primary=True,
     )
+    # 视频资产:额外抽首帧作为封面图,挂成同一 Asset 下的 image 文件,供任务中心/列表显示缩略图
+    if "video" in content_type:
+        try:
+            video_bytes = fileobj.getvalue() if isinstance(fileobj, BytesIO) else b""
+        except Exception:  # noqa: BLE001
+            video_bytes = b""
+        poster = _generate_video_poster(video_bytes=video_bytes, team=team, project=project, asset_id=asset_id)
+        if poster:
+            AssetFile.objects.create(
+                asset=asset,
+                object_key=poster.object_key,
+                bucket=poster.bucket,
+                content_type=poster.content_type,
+                size_bytes=poster.size_bytes,
+                is_primary=False,
+            )
     return asset