docs(conf): resolve the 36 ambiguous cross-references at their source

[JarryShaw]

Please follow the guide below

• You will be asked some questions, please read them carefully and answer honestly

• Put an x into all the boxes [ ] relevant to your pull request (like that [x])

• Use Preview tab to see how your pull request will actually look like

• Searched for similar pull requests

• Followed the coding style (make pylint, make mypy, make isort)

• make test passes, and a test case covers the change. Narrow runs only, listed below.

• Added a changelog entry under docs/source/changelog/ and regenerated CHANGELOG.md, if the change is user-visible: N/A — centralised in docs(changelog): shared 1.5.0 changelog — long-lived, merges last (#610, #616, #617, #618, #620) #657

What is the purpose of your pull request?

Tick the commit type your subject line carries.

• fix — corrects a defect
• feat — adds a feature
• perf — changes performance, not behaviour
• refactor — changes neither behaviour nor performance
• test — tests only
• docs — documentation only
• ci — workflows or build tooling
• release — bumps the version or rolls up a distribution
• chore — anything else

---

Summary

The docs build gave 36 "more than one target found" warnings. They are fixed at their source; the build now has 0, with no new warnings of any kind (clean -E builds, compared by page, kind and reference).

• dict, type, set (25): Sphinx's fuzzy suffix search matched registry members such as TCP.dict. A doctree-read hook in conf.py removes the fuzzy flag from implicit references to builtin names; explicit roles keep their search.
• http, Echo (4): napoleon split enum-member docstrings at a URL's colon into a fake Type field, on 51 members. A save/restore pair around napoleon (priorities 400/600) undoes that.
• TypeVars _AT, _IT, _BT, _DT (7): 44 hand-written directives repeated their module in the name. They take the bare name now, and links reach the right module's TypeVar.
• Tests: tests/project/test_docs_ambiguous_xrefs_1775_unit.py pins the hooks with real Sphinx nodes, the event wiring, and the directive names. The Sphinx-dependent tests skip in CI behind a declared HAS_SPHINX gate. Each hook, wiring line and priority fails a test when mutated.
• Follow-up: the convention "a hand-written directive takes the bare name under its .. module::" belongs in documentation.rst, which chore: drop stale build leftovers and move the examples' READMEs to Markdown (#1773) #1780 is editing.

Closes #1775

[JarryShaw]

Verdict: GOOD TO GO at 4041fe34a. A Sonnet cross-review (author: Opus) ran its own clean builds: 36 ambiguity warnings became 0, and the other 18 warnings are unchanged. It diffed all 198 pages' links: 25 builtin links now reach the Python docs, the TypeVar links reach the right module, and nothing else changed. A follow-up added tests for setup()'s event wiring; a Sonnet check confirmed each of eight mutations fails a test.