When a chat history contains a name-card message (msg_type=42), the
dispatcher in `_format_message_text` had no case for `base_type == 42`,
so it fell through to the generic non-text branch:
elif base_type != 1:
type_label = format_msg_type(local_type)
text = f"[{type_label}] {text}" if text else f"[{type_label}]"
`text` for type=42 is the full raw `<msg ...>` element, so chat history
exports emitted `[名片] <msg username="..." antispamticket="v2_..."
brandIconUrl="https://wx.qlogo.cn/..." bigheadimgurl="..." ... />`.
That payload has two problems:
1. It leaks anti-spam tokens (`antispamticket`) and head-image CDN URLs
into chat logs that are routinely piped to LLMs and other downstream
tools.
2. The raw XML drowns out the actual signal — a human or an LLM reading
the chat just wants to know "X shared Y's contact".
This PR adds `_format_namecard_text(content)` that pulls only the three
useful attributes:
- `nickname` — display name
- `username` — wxid (annotated as "公众号" when prefixed `gh_`)
- `certinfo` — user-authored bio
and wires it into the dispatch chain via a new `elif base_type == 42:`
branch, sitting alongside the existing `49` (app message) handler. It
reuses `_parse_xml_root` and `_collapse_text` — no new helpers
introduced.
Tests: 7 cases in `tests/test_namecard_format.py` covering the realistic
shape (with antispamticket / brand URLs that must NOT appear in output),
official accounts (`gh_*`), missing certinfo, missing nickname, missing
both identifiers, and broken-XML fallthrough.
All 158 tests pass locally (151 baseline + 7 new).
