V119: Add trash support to storage folders + widen the annotations kind CHECK for the "dimension" kind.

Two unrelated changes folded into one version since neither has shipped yet:

1. Folder trash — trashed_at TIMESTAMPTZ column on phoenix_kit_media_folders for soft-delete, mirroring the V99 addition on phoenix_kit_files. Folders with a non-nil trashed_at are in the trash bucket and can be restored or permanently deleted. Trashing a folder recursively trashes its descendants + every file inside the subtree (handled in Storage.trash_folder/2); restore reverses the operation.

2. Dimension annotation — Etcher 0.2.4 adds a "dimension" annotation kind (line with arrows on both ends + a slidable label, for measurement / architectural use cases). Drops and re-adds phoenix_kit_annotations_kind_check so 'dimension' passes the V118 CHECK.

All operations are idempotent.