docs: cut 1.3.2, and say plainly that the wheel did not change

tools/ and tests/ are not in the package, so this release ships library
code identical to 1.3.1 byte for byte. Anyone who only uses the library
can skip it. Saying so up front is better than letting someone diff the
wheel and wonder what they missed.

What is in it: the retention script can now be told which table it may
delete from, and the Postgres tests no longer touch the table three
migration projects also write to.

The --table entry documents the failure it prevents rather than just
the flag. search_path starts with "$user", so the same command run as a
different role can resolve to a different table, and the script's own
printout of what it resolved lands in the same run as the DELETE.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "polygateway"
-version = "1.3.1"
+version = "1.3.2"
 description = "PolyGateway：实验室统一的大语言模型（LLM/VLM/OCR）调度与中转库——多源、限流、重试、熔断、缓存、遥测"
 # registry 包页面的正文只认这一项:缺了页面就是一片空白(1.1.2 的教训,twine 会警告
 # long_description missing 但不阻塞上传)。README 在打包时被固化进产物,发布后再改无效。