fix(deploy): fix all conditional class attributes for missing models

Fix AttributeError in evidence, escalation, and risk services when
model_governance_pack is not available. All class-level attributes
that depend on imported types now check both GOVERNANCE_MODELS_AVAILABLE
AND that the specific type is not None before use.

Author: Lexecon Dev

src/lexecon/escalation/service.py

@@ -72,7 +72,7 @@ class EscalationConfig:
     AUTO_ESCALATE_RISK_LEVEL = RiskLevel.CRITICAL if GOVERNANCE_MODELS_AVAILABLE else None
 
     # SLA deadlines by priority (in hours) — only define if models available
-    if GOVERNANCE_MODELS_AVAILABLE:
+    if GOVERNANCE_MODELS_AVAILABLE and EscalationPriority is not None:
         SLA_DEADLINES = {
             EscalationPriority.CRITICAL: 2,  # 2 hours
             EscalationPriority.HIGH: 8,  # 8 hours

src/lexecon/evidence/service.py

@@ -61,7 +61,7 @@ class EvidenceConfig:
     """Configuration for evidence service."""
 
     # Default retention periods by artifact type (in days) — only define if models available
-    if GOVERNANCE_MODELS_AVAILABLE:
+    if GOVERNANCE_MODELS_AVAILABLE and ArtifactType is not None:
         DEFAULT_RETENTION_PERIODS = {
             ArtifactType.DECISION_LOG: 2555,  # 7 years
             ArtifactType.POLICY_SNAPSHOT: 2555,  # 7 years

src/lexecon/risk/service.py

@@ -75,7 +75,7 @@ class RiskScoringEngine:
     }
 
     # Risk level thresholds (defined conditionally to avoid import errors)
-    if GOVERNANCE_MODELS_AVAILABLE:
+    if GOVERNANCE_MODELS_AVAILABLE and RiskLevel is not None:
         RISK_THRESHOLDS = {
             RiskLevel.CRITICAL: 80,  # >= 80
             RiskLevel.HIGH: 60,  # 60-79