docs: a doc comment whose first line has a colon renders its prose as a Type field #2745

Describe the bug
When an attribute doc comment (#:) has a colon on its first line, Napoleon parses that line as "type: description". The text before the colon goes into a Type field and drops out of the prose. Usually there is no warning, so nothing catches it. #2744 fixed the two cases that did warn: IGMPv3 Query.checksum and the DTLS reassembler's __protocol_type__.

Reproduction
Build docs/ at ab7be2fb0 in a clean venv. In the generated page for pcapkit.protocols.data.internet.igmp, the group attribute shows Type: Group address and its description starts after the colon. Other first lines with the same shape, found by the #2744 review (some may be false positives):

• Group address: in protocols/data/internet/igmp.py and igmpv3.py.
• Extension data: in protocols/data/application/tls.py.
• Unified-header first octet: in protocols/schema/application/dtls.py.
• First length octet: in protocols/schema/internet/mh.py.
• Protocol Type: in the GRE schema and data modules.
• Similar comments in hopopt, ipv6_opts, ipv4, tcp, raw, dccp and radiotap, in the traceflow and reassembly data modules, and in corekit/checksum/internet.py.
• The "What __proto__ is keyed by" comments on the Frame, Link, Internet, PCAPNG and pcap Frame classes.

Also, in #2744 the netlink footnote marker leaks framing* into that page's og:description and meta description.

Expected behavior
Every #: comment renders as prose with no stray Type field, and a project test fails on any new first-line colon that Napoleon would misread.

System information
Linux, CPython 3.15.2, Sphinx 9.2.0, sphinx-autodoc-typehints 3.17.2/3.17.4, checkout ab7be2fb0.