v0.18.0: MCP entity-graph CRUD, lifecycle validation, curl -o /dev/null fix

- create_entity, set_entity_state, end_relationship MCP tools
- update_entity_attributes now triggers check derivation via EnsureEntityChecks
- shared db.EnsureEntityChecks + db.ValidateTransition hooks (HTTP + MCP parity)
- curl -o /dev/null now classified read_only (was config_mutation)
- db.ErrTransitionInvalid sentinel for HTTP error-type accuracy
- SOUL.md: capability escalation, self-grounding, exploration budget rules
- Runbook: oikos check lifecycle for agent self-knowledge

internal/db/sqlcgen/models.go

@@ -380,6 +380,8 @@ type RelationshipType struct {
 	Cardinality string
 	Description *string
 	CreatedAt   time.Time
+	// Which end of this edge depends on the other. forward = target depends on source. backward = source depends on target. none = no runtime dependency. Drives blast_radius().
+	BlastDirection string
 }
 
 type RiskClass struct {