Prepare Perform 1.8.0 settings and packaged validation

[mehul0810]

Settings edits made during a pending save or its success notification could be treated as saved even though they were never submitted. The saved baseline now advances only from the acknowledged submission, retaining later edits for another save. Numeric cache select values also persist correctly, with the established runtime defaults retained by full-form saves.

This candidate targets release/1.8.0 at df4b9983ac565dc01620821172a6fae6d943c186. It adapts the select/default fixes reviewed in #259 while preserving existing extension keys and legacy lists; it does not include that PR's new schema limits. #259 remains open and unmerged. Refs #201 and #259.

Validation and CI changes:

• Local JavaScript/CSS lint, 13 Jest suites / 45 tests, PHP lint, PHPStan, and changed-PHP PHPCS pass.
• PHPUnit passes: 150 tests / 492 assertions on native PHP 7.4, 8.1 and 8.5. Repository-wide PHPCS retains pre-existing violations outside the changed PHP files.
• Added Jest execution to CI, PHP 7.4 to the PHPUnit matrix, and ZIP integrity checks with a downloadable CI artifact.
• WordPress smoke tests now install the built ZIP, on WordPress 7.1.3 / PHP 8.3. Added browser coverage for pending saves, success-notice edits, keyboard submission and interrupted retries.
• Independent packaged upgrade/rollback proof is in progress. Tested up to: 7.1 was already present and is retained.

Release gates remain open: exact final CI artifact proof; reconciliation of the parallel dependency update; and a release decision for #264, which was reproduced using real WordPress options and overlapping native PHP requests but remains a Backlog warmup-reliability issue. Persistent-object-cache and multisite variants of that race are unverified. No release publication, protected merge, or production deployment is part of this PR.

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