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

sql/store.sql

@@ -69,6 +69,7 @@ CREATE TABLE annotations (
   id VARCHAR(256) NOT NULL,
   layer VARCHAR(256) NOT NULL,
   body_kind VARCHAR(24) NOT NULL CHECK (body_kind IN ('gloss', 'claim-link', 'symbol', 'comment', 'caveat', 'question', 'exercise', 'citation-context', 'prerequisite', 'crosslink', 'translation', 'description', 'generated')),
+  category VARCHAR(12) CHECK (category IN ('comment', 'context', 'critique', 'question', 'correction', 'feedback', 'resource')),
   status VARCHAR(10) NOT NULL CHECK (status IN ('proposed', 'confirmed', 'rejected', 'withdrawn')),
   receipt VARCHAR(32),
   creator VARCHAR(256) NOT NULL,