v0.8.0

Language support

• Track phel-lang main (ahead of v0.41.0) for the unreleased interop work: corpus now covers defenum, hydrate, bean, iterator-seq, the reflect enum/attribute bridges (enum->keyword, keyword->enum, enum-values, class-attributes, method-attributes, property-attributes), and html-response / json-response.
• Add the defenum enum form: completion (defenum* special form), keyword highlighting, and a defenum snippet.
• Add php/ref (by-reference PHP interop) to the php/* special-form completion list; it already highlighted via the generic php/ rule.