feat: comment categories; emend, relink and resolve corrections

scienting-layer/1: an optional, fixed category on comment, caveat and
question bodies (comment, context, critique, question, correction,
feedback, resource).

Corrections: emend fixes the authors' own slip and keeps what was printed
(a run's printed), never lowering fidelity or a witness match; relink sets
or removes what a citation names; resolve sets a reference's resolution.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017R7sgDNvUGWY2zFPCq2JH6

spec/13-database.md

@@ -39,7 +39,7 @@ Unloading gives the package back byte for byte, and its manifest hash with it; t
 ## 13.4 The store tables
 
 `store.sql` adds what a team adds to its documents: `roster_keys`, `projects`, `members`, `project_documents`, `reading_paths`, `layers`, `annotations`, `annotation_targets` (derived, so a reader finds the annotations on a node), `datasets`, `dataset_values`, `digitizations`, `views`, `policies`, `submissions` and `grades`.
-Each keeps its record whole in a `record` or `descriptor` column, with the columns a query needs beside it.
+Each keeps its record whole in a `record` or `descriptor` column, with the columns a query needs beside it, such as an annotation's `body_kind` and its `category`, which is NULL when the body has none.
 
 ## 13.5 The bundle