Add RuleConventionsTest to enforce rule registration conventions

[mglaman]

Adds tests/src/RuleConventionsTest.php which parses rules.neon,
extension.neon, and bleedingEdge.neon and asserts that every rule is
toggleable: registered via conditionalTags with a boolean default under
parameters.drupal.rules, opt-in rules enabled in bleedingEdge.neon, and
no new rules added directly under rules:. Graduated rules (default
true) are tracked via an explicit allowlist.

Fixes the pre-existing convention violation surfaced by the test:
pluginManagerInspectionRule was opt-in (false default) but missing from
bleedingEdge.neon.

Adds AGENTS.md documenting the conventions for contributors and agents,
and nette/neon as a dev dependency for parsing the neon files.

Closes #971

https://claude.ai/code/session_01AAChSrMEaL4S6st2ET2JRF

[Copilot]

Pull request overview

This PR adds an automated PHPUnit guardrail to enforce this repository’s PHPStan rule registration conventions (toggleable rules via conditionalTags + parameters.drupal.rules, and a frozen legacy rules: list), and documents the conventions for contributors.

Changes:

• Add RuleConventionsTest that parses rules.neon, extension.neon, and bleedingEdge.neon to enforce rule toggleability conventions.
• Add nette/neon (dev) dependency to decode NEON config in tests.
• Document rule registration conventions in CLAUDE.md.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
tests/src/RuleConventionsTest.php	New PHPUnit test enforcing rule registration/toggleability conventions across NEON configs.
composer.json	Adds nette/neon to require-dev for NEON parsing in tests.
CLAUDE.md	Documents the rule registration conventions and graduation workflow.

Comments suppressed due to low confidence (2)

tests/src/RuleConventionsTest.php:115

• The test name testConditionalRulesHaveFalseDefaultInExtensionNeon is misleading because the body explicitly allows (and asserts) true defaults for parameters listed in GRADUATED_RULES. Rename the test to reflect the actual convention being enforced (e.g., “conditional rules have a boolean default; non-graduated default false”).

    public function testConditionalRulesHaveFalseDefaultInExtensionNeon(): void
    {
        $defaults = $this->extensionRuleDefaults();

        foreach ($this->conditionalRuleParameters() as $parameter) {

tests/src/RuleConventionsTest.php:167

• The comment says graduated rules “must not be listed in bleedingEdge.neon”, but the test currently just continues when the default isn’t false and never asserts absence in $bleedingEdge. Add an assertion that graduated (default true) rule parameters are not present in bleedingEdge.neon so the convention is actually enforced.

        foreach ($this->conditionalRuleParameters() as $parameter) {
            if (!array_key_exists($parameter, $defaults) || $defaults[$parameter] !== false) {
                // Graduated rules (default `true`) are already on by default and
                // must not be listed in bleedingEdge.neon.
                continue;