ci: enforce regression tests and harden import loading

[somethingwithproof]

Summary

• Repair the integration workflow package installation, MySQL authentication, lint redirection, and pinned Cacti checkout.
• Make every standalone PHP regression script a required CI step.
• Realign stale regression assertions with the current sequence-bounded alert query and centralized import helper.
• Reject empty or unreadable XML import files without triggering PHP 8 fread(..., 0) ValueError failures.

PHP compatibility

The import reader uses PHP 8.0-compatible union types and try/finally; it does not introduce PHP 8.1-only syntax.

Validation

• All eight regression scripts pass.
• functions.php passes PHP lint.
• actionlint passes.
• The repository pre-push review gate passed with no critical, high, or medium findings.

This supersedes #327. PRs #326 and #320 should be rebased onto develop after this lands so they inherit the corrected CI gate without duplicating workflow commits.

[Copilot]

Pull request overview

This PR repairs the plugin’s GitHub Actions integration workflow to make it deterministic and fix several workflow/runtime issues encountered across plugins, without changing any plugin PHP code.

Changes:

• Pin the Cacti core checkout to release/1.2.31 to avoid testing against a moving default branch.
• Fix find -exec php -l redirection placement so actionlint/shellcheck no longer flags SC2227.
• Fix MySQL authentication by constructing --defaults-file using $HOME inside the run: block (avoids literal ~), and remove the PHP-version-suffixed Apache module install in favor of libapache2-mod-php.

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[somethingwithproof]

Final maintenance audit is complete: this PR is a single-purpose, one-commit change, is based on current develop, has no unresolved review threads, and all checks are green. GitHub still requires approval from someone other than the last pusher. @TheWitness, please review/approve and merge this first; #327 is superseded by this PR and the remaining Syslog branches will be rebased after it lands.

[somethingwithproof]

@TheWitness #329 is now a single rebased commit with all GitHub checks green. It makes the regression scripts blocking, fixes the integration matrix, and includes the PHP 8 zero-byte import guard found by the review gate. The branch-protection rule requires approval from someone other than the last pusher; please review/approve and squash-merge when ready. #320 and #326 are intentionally waiting to rebase onto this rather than duplicating its workflow commit.