feat(site): 页头加上 GitHub 仓库与 Telegram 频道链接

做成配置项 LDR_HEADER_LINKS，格式 "名称|地址" 逗号分隔，
不硬编码 —— 以后换地址改环境变量即可，不用动代码。

默认值：
  GitHub          https://github.com/lowseekai/let-deals-radar
  Telegram 频道   https://t.me/LowSeekNews

细节
- 解析时跳过非法项（缺分隔符、地址不是 http 开头）
- 未配置则整段不输出，不留空占位
- 外链带 target=_blank + rel=noopener

验证：235 测试通过（新增 4 个）。

letdeals/config.py

@@ -63,6 +63,32 @@ SITE_DESC = _env(
 SITE_URL = _env("LDR_SITE_URL", "").rstrip("/")
 SITE_FOOTER = _env("LDR_SITE_FOOTER", "")
 
+# 页头的附加链接，格式 "名称|地址"，多项用逗号分隔。
+# 例：LDR_HEADER_LINKS="GitHub|https://github.com/x/y, Telegram|https://t.me/z"
+# 留空则不显示 —— 不影响现有布局。
+HEADER_LINKS_RAW = _env(
+    "LDR_HEADER_LINKS",
+    "GitHub|https://github.com/lowseekai/let-deals-radar,"
+    " Telegram 频道|https://t.me/LowSeekNews",
+)
+
+
+def _parse_header_links(raw: str) -> list[tuple[str, str]]:
+    """把 "名称|地址,..." 解析成 [(名称, 地址)]，非法项跳过。"""
+    out: list[tuple[str, str]] = []
+    for chunk in (raw or "").split(","):
+        chunk = chunk.strip()
+        if not chunk or "|" not in chunk:
+            continue
+        name, url = chunk.split("|", 1)
+        name, url = name.strip(), url.strip()
+        if name and url.startswith(("http://", "https://")):
+            out.append((name, url))
+    return out
+
+
+HEADER_LINKS = _parse_header_links(HEADER_LINKS_RAW)
+
 
 # --------------------------------------------------------------------------
 # 数据源

letdeals/render.py

@@ -153,6 +153,19 @@ def _json_for_script(obj) -> str:
             .replace("&", "\\u0026"))
 
 
+def _header_links_html() -> str:
+    """渲染页头附加链接。未配置时返回空串（不影响布局）。"""
+    links = getattr(config, "HEADER_LINKS", None) or []
+    if not links:
+        return ""
+    parts = []
+    for name, url in links:
+        parts.append('<span><a href="%s" target="_blank" rel="noopener">%s</a>'
+                     '</span>' % (html.escape(url, quote=True),
+                                  html.escape(name)))
+    return "\n    ".join(parts)
+
+
 SITE_TEMPLATE = r"""<!DOCTYPE html>
 <html lang="zh-CN">
 <head>
@@ -301,6 +314,7 @@ footer{margin-top:28px;color:var(--muted);font-size:12px;line-height:1.9}
     <span>共 <b id="m-total">@@COUNT@@</b> 条</span>
     <span>生成于 <b>@@GENERATED@@</b></span>
     <span><a href="data/deals.json">原始 JSON</a></span>
+    @@HEADER_LINKS@@
   </div>
 </header>
 
@@ -668,6 +682,7 @@ def build_site(payload: dict, out_dir=None, verbose: bool = True) -> str:
                 .replace("@@EVENT_CN@@", json.dumps(EVENT_CN, ensure_ascii=False))
                 .replace("@@AVAIL_CN@@", json.dumps(AVAIL_CN, ensure_ascii=False))
                 .replace("@@FXNOTE@@", html.escape(config.FX_NOTE))
+                .replace("@@HEADER_LINKS@@", _header_links_html())
                 .replace("@@FOOTER@@",
                          html.escape(config.SITE_FOOTER) if config.SITE_FOOTER
                          else ""))

tests/test_render.py

@@ -289,6 +289,48 @@ def test_forum_links_corrupt_file_is_safe(tmp_path):
         mp.undo()
 
 
+def test_header_links_rendered(tmp_path):
+    """页头应渲染配置的附加链接（GitHub / Telegram）。"""
+    render.build_site(_sample_payload(), str(tmp_path), verbose=False)
+    html = open(os.path.join(tmp_path, "index.html"), encoding="utf-8").read()
+
+    links = render.config.HEADER_LINKS
+    assert links, "默认应配置页头链接"
+    for name, url in links:
+        assert name in html, "缺少链接名：%s" % name
+        assert url in html, "缺少链接地址：%s" % url
+    assert 'rel="noopener"' in html
+
+
+def test_header_links_empty_is_safe(tmp_path):
+    """未配置页头链接时不报错、不留占位符。"""
+    import pytest as _pytest
+    mp = _pytest.MonkeyPatch()
+    mp.setattr(render.config, "HEADER_LINKS", [])
+    try:
+        render.build_site(_sample_payload(), str(tmp_path), verbose=False)
+    finally:
+        mp.undo()
+    html = open(os.path.join(tmp_path, "index.html"), encoding="utf-8").read()
+    assert "@@HEADER_LINKS@@" not in html
+
+
+def test_parse_header_links():
+    """解析 "名称|地址,..."，非法项跳过。"""
+    from letdeals.config import _parse_header_links
+    got = _parse_header_links(
+        "GitHub|https://github.com/x, Bad|not-a-url, ,"
+        " TG|https://t.me/y")
+    assert got == [("GitHub", "https://github.com/x"),
+                   ("TG", "https://t.me/y")]
+
+
+def test_parse_header_links_empty():
+    from letdeals.config import _parse_header_links
+    assert _parse_header_links("") == []
+    assert _parse_header_links("没有分隔符") == []
+
+
 def test_link_rendering_both_cases(tmp_path):
     """链接区两种形态：有论坛帖=主+次两个；无=只有原帖。"""
     render.build_site(_sample_payload(), str(tmp_path), verbose=False)