BUGFIX: false positive: interactive flow content inside <details>

[johanrd]

• Premise 1: The permitted content of <details> is "one <summary> element, followed by flow content" — see the spec's own example mixing <input> and <label> as siblings of <summary>.
• Premise 2: Flow content includes <label>, <input>, <button>, <form>.
• Conclusion: Interactive content as a sibling of <summary> inside <details> is spec-conformant and should not be flagged.

Narrow fix: <details> stays in the interactive set, so the rule still flags:

• <details> inside another interactive element (e.g. <button><details/></button>)
• <summary> when it is not the first non-whitespace child of <details>

Only the case of "interactive element in the disclosed panel (sibling of <summary>)" is exempted — <details>'s own children other than <summary> no longer see <details> as an interactive ancestor.

Upstream [email protected] has the same false positive; fixing here is pragmatic since ember-template-lint is being de-emphasized.