Fix get_hot_posts ignoring the limit parameter

[Osamaali313]

Problem

XueqiuChannel.get_hot_posts(limit) (agent_reach/channels/xueqiu.py) documents its argument as limit: 最多返回条数（上限 50） ("max number of posts to return, up to 50"), but the request hard-codes the page size to count=20:

data = _get_json(
    "https://xueqiu.com/v4/statuses/public_timeline_by_category.json"
    "?since_id=-1&max_id=-1&count=20&category=-1"
)
items = data.get("list") or []
results = []
for item in items[:limit]:
    ...

The server therefore never returns more than 20 posts, and the later items[:limit] slice can only shrink those 20 — it can never reach the documented maximum. So get_hot_posts(limit=50) silently returns just 20.

Evidence (siblings prove intent)

The two sibling methods in the same file thread limit into the page-size parameter:

• search_stock: f"?code={...}&size={limit}"
• get_hot_stocks: f"?size={limit}&type={stock_type}"

Both then slice items[:limit]. get_hot_posts is the only one that omits limit from the request.

Reproduction

Against a stub that honors the URL's page-size (the same contract the size={limit} siblings rely on):

call	before	after
get_hot_posts(limit=50)	20 ❌	50 ✅

Fix

f"?since_id=-1&max_id=-1&count={limit}&category=-1"

Matches the size={limit} pattern of both siblings so the requested count is honored.

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[Panniantong]

感谢贡献。该修复已在 #578 以保留你作者身份的提交 31b028f 重实现并合并到 main；同时覆盖 limit 上限 50、零值不请求、负值快速失败等边界。全量测试与 CI 已通过，因此关闭此旧 PR。