feat(read): 已读功能 — 每账号标已读,列表默认隐藏

需求: 每个账号可标已读,已读过的文章刷新/重载后不在 24h feed 中显示。

设计:
- 新表 article_reads (user_id, article_id, read_at) 复合主键,on-delete CASCADE
- 迁移 0007_article_reads
- /me/reads/{id} POST/DELETE 标记 / 取消(幂等,PG upsert on_conflict_do_nothing)
- /me/reads GET 列出已读 IDs(默认 7 天,limit 500)
- articles.py 列表查询加 hide_read=true 参数(默认 true),用 NOT EXISTS 排除已读
- ArticleListItem / ArticleDetail schema 加 is_read 字段

前端:
- types 加 is_read + readsApi(mark/unmark/list)
- Feed 列表:
    顶部加 '隐藏已读' 开关,默认 ON
    每张卡片加 '标为已读 / 标为未读' 按钮(乐观更新,失败回滚)
    已读卡片 opacity 0.7 + 灰背景,标识弱化
- ArticleDetail 详情页操作栏加 '标为已读' 按钮(同样乐观)

backend/app/api/me.py

@@ -1,15 +1,18 @@
-"""/me 当前用户信息 + 翻译配额。"""
+"""/me 当前用户信息 + 翻译配额 + 已读文章。"""
 from __future__ import annotations
 
-from datetime import datetime, timezone
+from datetime import datetime, timedelta, timezone
 
-from fastapi import APIRouter, Depends
+from fastapi import APIRouter, Depends, HTTPException, status
 from pydantic import BaseModel
+from sqlalchemy import and_, delete, select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.config import settings
 from app.core.deps import get_current_user
 from app.database import get_session
+from app.models.article import Article
+from app.models.article_read import ArticleRead
 from app.models.user import User
 from app.redis_client import get_redis
 
@@ -34,6 +37,17 @@ class UsageOut(BaseModel):
     pct_used: float
 
 
+class ReadToggleResponse(BaseModel):
+    article_id: int
+    is_read: bool
+
+
+class ReadListResponse(BaseModel):
+    """已读文章 ID 列表(给前端用,Feed 列表展示)."""
+    article_ids: list[int]
+    total: int
+
+
 @router.get("", response_model=MeOut)
 async def me(user: User = Depends(get_current_user)):
     return MeOut(
@@ -66,3 +80,65 @@ async def usage(
         buffered_quota=buffered,
         pct_used=round(used / quota * 100, 2) if quota else 0.0,
     )
+
+
+# === 已读文章(per-user) ===
+@router.post("/reads/{article_id}", response_model=ReadToggleResponse)
+async def mark_read(
+    article_id: int,
+    user: User = Depends(get_current_user),
+    session: AsyncSession = Depends(get_session),
+):
+    """标记文章为已读(幂等,重复调用不报错)。"""
+    # 先确认文章存在(不存在返 404,避免 FK 报错)
+    exists = (await session.execute(select(Article.id).where(Article.id == article_id))).scalar_one_or_none()
+    if not exists:
+        raise HTTPException(status.HTTP_404_NOT_FOUND, "Article not found")
+    # 用 INSERT ... ON CONFLICT DO NOTHING (PG 原生)— 等价 upsert 跳过
+    from sqlalchemy.dialects.postgresql import insert as pg_insert
+    stmt = pg_insert(ArticleRead).values(user_id=user.id, article_id=article_id).on_conflict_do_nothing(
+        index_elements=["user_id", "article_id"]
+    )
+    await session.execute(stmt)
+    await session.commit()
+    return ReadToggleResponse(article_id=article_id, is_read=True)
+
+
+@router.delete("/reads/{article_id}", response_model=ReadToggleResponse)
+async def unmark_read(
+    article_id: int,
+    user: User = Depends(get_current_user),
+    session: AsyncSession = Depends(get_session),
+):
+    """取消已读(幂等)。"""
+    stmt = delete(ArticleRead).where(
+        and_(ArticleRead.user_id == user.id, ArticleRead.article_id == article_id)
+    )
+    res = await session.execute(stmt)
+    await session.commit()
+    return ReadToggleResponse(article_id=article_id, is_read=False)
+
+
+@router.get("/reads", response_model=ReadListResponse)
+async def list_reads(
+    since: datetime | None = None,
+    limit: int = 500,
+    user: User = Depends(get_current_user),
+    session: AsyncSession = Depends(get_session),
+):
+    """列出当前用户已读文章 ID(给 Feed 过滤 / 已读时间线用)。
+
+    - since: 只返回 read_at >= since 的(默认 7 天前,避免数据爆炸)
+    - limit: 最多返回多少(默认 500)
+    """
+    if since is None:
+        since = datetime.now(timezone.utc).replace(tzinfo=None) - timedelta(days=7)
+    stmt = (
+        select(ArticleRead.article_id)
+        .where(ArticleRead.user_id == user.id, ArticleRead.read_at >= since)
+        .order_by(ArticleRead.read_at.desc())
+        .limit(min(limit, 2000))
+    )
+    rows = (await session.execute(stmt)).all()
+    ids = [r[0] for r in rows]
+    return ReadListResponse(article_ids=ids, total=len(ids))