Proves Slice 1's contract through the production routes and the real client:
a code-built drawing is packaged, uploaded, found by cut type, material, grade
and thickness among decoys, downloaded and read back with identical program
text; a stale If-Match update raises a conflict and leaves the current
revision, its package hash and the history unchanged. Archive, restore,
metadata edits and duplicate ids are exercised the same way.
Documents the /api/drawings contract, schema v4 and the fact that the backup
manifest and restore check do not yet verify drawings.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
