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

vectors/projection-groups.jsonl

@@ -9,3 +9,5 @@
 {"cases":["cite-mark","cite-as-text"],"differ":"match_hash","id":"cite-structure"}
 {"cases":["hyphen-before-digit","en-dash-before-digit"],"id":"dashes-align","same":"align_key"}
 {"cases":["hyphen-before-digit","en-dash-before-digit"],"differ":"text_hash","id":"dashes-text"}
+{"cases":["emended","as-printed"],"id":"emended-match","same":"match_hash"}
+{"cases":["emended","as-printed"],"differ":"text_hash","id":"emended-text"}