Comments can now have documents attached via multipart/form-data upload.
New endpoint GET /api/documents/comment/{id} to list a comment's files.
Document entity gains a comment relation with cascade remove.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Create Comment entity with API Platform annotations (GET, PATCH, DELETE).
Add CommentController with POST (create), PATCH (resolve) and GET
(unresolved count) endpoints. Add migration for comments table and
piece reference unique index.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>