docs: sphinx-autodoc-typehints 3.15.0 renames the private _resolver that conf.py imports, so the next dependency bump breaks the docs build #1856

docs/source/conf.py:23 imports resolve_type_guarded_imports from sphinx_autodoc_typehints._resolver. 3.15.0 (on PyPI since 2026-10-16 20:30Z) has no _resolver: the function moved to _resolve/guards/run.py and is re-exported from _resolve. docs/requirements.txt pins 3.13.9, and the weekly dependency PRs (e.g. #1629) move that pin. The next one fails the docs build at import, loudly, as the comment above the import intends.

3.15.0 also fixes three defects measured on the current docs:

• overload signatures render every type as unlinked source text, builtins included, e.g. → Data_Packet on ProtocolBase._read_packet;
• Self is emitted with the py:class role and never links;
• TypedDict bases imported from typing_extensions never link.

All three render correctly in a 3.15.0 build with only the import changed.

Fix:

• bump the pin to 3.15.x and import from _resolve;
• diff a clean build;
• re-check the conf.py hooks that reach into the extension.

3.15.0 also changes some signature rendering (e.g. PCAPIO(fname, **kwargs)), so verify #1859 and #1860 after this.