Extract duplicated reverse/1 to shared utility

[StephanMeijer]

Problem

Three modules each define their own private reverse/1 function that recursively reverses nested list structures. The implementations are nearly identical with minor clause variations:

• BlockNote.Writer — 5 clauses (handles :content, :rows, :cells)
• Tiptap.Writer — 3 clauses (handles :content)
• Tiptap.Reader — 3 clauses (handles :children)

The BlockNote version is a superset of the other two.

Why these exist

The readers/writers build lists using [head | tail] prepend patterns for performance, then reverse at the end. This is standard Elixir, but the reversal logic for nested tree structures is non-trivial and shouldn't be duplicated.

Proposal

Extract to a shared utility, e.g. DocSpec.Core.Util.Tree.reverse/1, that handles all known key patterns (:children, :content, :rows, :cells). The function should be generic enough to work with any nested struct/map that uses list-valued keys.

Files

• lib/docspec/core/blocknote/writer.ex (lines 714–731)
• lib/docspec/core/tiptap/writer.ex (lines 275–283)
• lib/docspec/core/tiptap/reader.ex (lines 353–361)