Align artifacts with canonical URT v5.1 specification

Fixes inconsistencies discovered during audit against urt-taxonomy/:

- urt_profile ENUM: Add 'lite' and 'core' profiles (was missing)
- USN format: Use canonical regex from spec (was non-compliant)
- USN valence encoding: Add V0 (0) and V± (±) support
- USN grammar: Add Lite (URT:L:) and Core (URT:C:) formats
- Dimension codes: Fix temporal (TC/TR/TH/TF), evidence (ES/EI/EC),
  comparative (CR-N/CR-B/CR-W/CR-S) in decisions doc
- LLM contract: Full USN regex validation pattern

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.artifacts/ReviewIQ-Architecture-v3.2.md

@@ -140,7 +140,7 @@ CREATE TYPE urt_actionability AS ENUM ('A1', 'A2', 'A3');
 CREATE TYPE urt_temporal AS ENUM ('TC', 'TR', 'TH', 'TF');
 CREATE TYPE urt_evidence AS ENUM ('ES', 'EI', 'EC');
 CREATE TYPE urt_comparative AS ENUM ('CR-N', 'CR-B', 'CR-W', 'CR-S');
-CREATE TYPE urt_profile AS ENUM ('standard', 'full');
+CREATE TYPE urt_profile AS ENUM ('lite', 'core', 'standard', 'full');
 CREATE TYPE urt_confidence AS ENUM ('high', 'medium', 'low');
 CREATE TYPE urt_relation AS ENUM ('cause_of', 'effect_of', 'contrast', 'resolution');
 CREATE TYPE urt_entity_type AS ENUM ('location', 'staff', 'product', 'process', 'time', 'other');
@@ -411,15 +411,20 @@ ALTER TABLE review_spans
     ADD CONSTRAINT chk_no_self_relation
     CHECK (related_span_id IS NULL OR related_span_id != span_id);
 
--- USN format validation based on profile
--- Standard: V[+-0±]:I[123]:CODE (e.g., "V-:I2:J1.01")
--- Full: V[+-0±]:I[123]:CODE:S[123]:A[123]:T[CRHF]:E[SIC] (e.g., "V-:I3:J1.01:S2:A2:TC:ES")
+-- USN format validation based on profile (URT v5.1 canonical format)
+-- Lite:     URT:L:{domain}:{valence}{intensity}
+-- Core:     URT:C:{category}:{valence}{intensity}
+-- Standard: URT:S:{subcode}[+{sec}]:{valence}{intensity}:{S}{A}{T}.{E}.{CR}
+-- Full:     URT:F:{subcode}[+{sec}]:{valence}{intensity}:{S}{A}{T}.{E}.{CR}[:{causal}]
+-- Examples: URT:L:O:+2  |  URT:C:J1:-3  |  URT:S:J1.03:-2:22TC.ES.N  |  URT:F:J1.01:-3:23TR.ES.S:CD.O,MG.O
 ALTER TABLE review_spans
     ADD CONSTRAINT chk_usn_format
     CHECK (
         usn IS NULL OR
-        (profile = 'standard' AND usn ~ '^V[+\-0±]:I[123]:[OPJEAVR][1-4]\.[0-9]{2}$') OR
-        (profile = 'full' AND usn ~ '^V[+\-0±]:I[123]:[OPJEAVR][1-4]\.[0-9]{2}:S[123]:A[123]:T[CRHF]:E[SIC]$')
+        (profile = 'lite' AND usn ~ '^URT:L:[OPJEAVR]:[+\-0±][123]$') OR
+        (profile = 'core' AND usn ~ '^URT:C:[OPJEAVR][1-4]:[+\-0±][123]$') OR
+        (profile = 'standard' AND usn ~ '^URT:S:[OPJEAVR][1-4]\.[0-9]{2}(\+[OPJEAVR][1-4]\.[0-9]{2}){0,2}:[+\-0±][123]:[1-3][1-3]T[CRHF]\.E[SIC]\.[NBWS]$') OR
+        (profile = 'full' AND usn ~ '^URT:F:[OPJEAVR][1-4]\.[0-9]{2}(\+[OPJEAVR][1-4]\.[0-9]{2}){0,2}:[+\-0±][123]:[1-3][1-3]T[CRHF]\.E[SIC]\.[NBWS](:(CD|MG|SY)\.[STEOFRPCSHX](,(CD|MG|SY)\.[STEOFRPCSHX])*)?$')
     );
 
 -- Foreign keys for review_spans