Stop measuring vendored SDK code as this plugin's coverage

[whyisjake]

Coverage measures includes/Vendor/, which is third-party SDK code copied verbatim from upstream php-ai-client. Those files carry paths this plugin never calls, so the score reflects upstream's test suite rather than ours.

phpcs.xml.dist and phpstan.neon.dist already exclude that directory. This adds the same exclusion for coverage: an <exclude> in phpunit.xml.dist so the files never enter the clover report, and a new codecov.yml so they are absent from Codecov's view of it.

The percentage can move in either direction, since this removes covered lines as well as uncovered ones.

Testing

npm run test:php passes at 1571 tests, which confirms PHPUnit still parses the config; a malformed <coverage> block fails the run outright. Codecov's validator accepts codecov.yml and compiles the matcher to (?s:includes/Vendor/.*)\Z.

Not verified locally: that the clover report itself omits the files. Neither wp-env container has Xdebug or PCOV, so no coverage run is possible here. CI will show it on this PR.

---

AI assistance: Yes. Tool(s): Claude Code (Opus 5). Used for: identifying the gap during a code review of #1004, both edits, and this description.

@whyisjake — this attestation is deliberately left for you. The WordPress AI Guidelines require the contributor to understand every line submitted and explain it under review; that is not something an agent can satisfy on your behalf. Replace this block before merging.

🤖 Generated with Claude Code

https://claude.ai/code/session_01BRSJEyQyYp3XTeum8fiq3L

[github-actions]

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If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

Co-authored-by: whyisjake <whyisjake@git.wordpress.org>
Co-authored-by: justlevine <justlevine@git.wordpress.org>
Co-authored-by: dkotter <dkotter@git.wordpress.org>

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[github-actions]

✅ WordPress Plugin Check Report

✅ Status: Passed

📊 Report

All checks passed! No errors or warnings found.

---

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[justlevine]

Thanks so much for this PR @whyisjake 🙇

Please be mindful of doc-slop, both in in the PR description (that project maintainers need to read and evaluate) and in the diffs themselves (where it also becomes infectious to future AI-led contributions).

PS: Also big thanks for adding the AI Disclosure to the bottom of the PR description, it was immensely helpful to allow me not to worry about human "intent" and made it quick and easy to share feedback 🙌

[whyisjake]

Fair hit, thank you. The description ran 588 words for a 23-line change, and the diff carried eleven lines of comment over two lines of config.

Both are trimmed. The config comments now point at includes/Vendor/AiClient/README.md rather than restating the reasoning, which also removes a third copy of it that was free to drift from the other two.

The infectious point is the one that landed for me. A verbose comment in a config file is what the next contributor copies.

Kept the AI disclosure, since it was useful.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.50%. Comparing base (a7657e1) to head (7e28ba3).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #1007      +/-   ##
=============================================
+ Coverage      75.55%   81.50%   +5.95%     
+ Complexity      3381     2923     -458     
=============================================
  Files            138      122      -16     
  Lines          13081    11653    -1428     
=============================================
- Hits            9883     9498     -385     
+ Misses          3198     2155    -1043     

Flag	Coverage Δ
unit	81.50% <ø> (+5.95%)	⬆️

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[justlevine]

🙌
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