feat: executions, assertions y bucle reactivo en fn_operations

Añade Execution, Assertion, AssertionResult al paquete fn_operations.
Motor de evaluación de assertions con reescritura SQL automática.
Bucle reactivo: ExecuteAndReact evalúa assertions y cambia status de
entities (corrupted/stale) + auto-crea proposals en registry.
CLI fn ops: assertion (add/list/show/delete/eval) y execution (add/list/show).
Migración 002_executions_assertions.sql con FTS para assertions.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

fn_operations/models.go

@@ -78,6 +78,73 @@ type RelationInput struct {
 	Order      *int   `json:"order"`
 }
 
+// ExecutionStatus represents the result of a pipeline execution.
+type ExecutionStatus string
+
+const (
+	ExecSuccess ExecutionStatus = "success"
+	ExecFailure ExecutionStatus = "failure"
+	ExecPartial ExecutionStatus = "partial"
+)
+
+// Severity classifies the impact of an assertion failure.
+type Severity string
+
+const (
+	SeverityCritical Severity = "critical"
+	SeverityWarning  Severity = "warning"
+	SeverityInfo     Severity = "info"
+)
+
+// AssertionResultStatus represents the outcome of an assertion evaluation.
+type AssertionResultStatus string
+
+const (
+	ResultPass AssertionResultStatus = "pass"
+	ResultFail AssertionResultStatus = "fail"
+	ResultSkip AssertionResultStatus = "skip"
+)
+
+// Execution records a pipeline run with its metrics and outcome.
+type Execution struct {
+	ID         string          `json:"id"`
+	PipelineID string          `json:"pipeline_id"`
+	RelationID string          `json:"relation_id"`
+	Status     ExecutionStatus `json:"status"`
+	StartedAt  time.Time       `json:"started_at"`
+	EndedAt    *time.Time      `json:"ended_at"`
+	DurationMs *int64          `json:"duration_ms"`
+	RecordsIn  *int64          `json:"records_in"`
+	RecordsOut *int64          `json:"records_out"`
+	Error      string          `json:"error"`
+	Metrics    map[string]any  `json:"metrics"`
+	CreatedAt  time.Time       `json:"created_at"`
+}
+
+// Assertion is a formal quality rule evaluated against an entity.
+type Assertion struct {
+	ID          string   `json:"id"`
+	EntityID    string   `json:"entity_id"`
+	Name        string   `json:"name"`
+	Kind        string   `json:"kind"` // free text: range, null, statistical, consistency, freshness, ...
+	Rule        string   `json:"rule"`
+	Severity    Severity `json:"severity"`
+	Description string   `json:"description"`
+	Active      bool     `json:"active"`
+	CreatedAt   time.Time `json:"created_at"`
+}
+
+// AssertionResult records one evaluation of an assertion.
+type AssertionResult struct {
+	ID          string                `json:"id"`
+	AssertionID string                `json:"assertion_id"`
+	ExecutionID string                `json:"execution_id"`
+	Status      AssertionResultStatus `json:"status"`
+	Value       map[string]any        `json:"value"`
+	Message     string                `json:"message"`
+	EvaluatedAt time.Time             `json:"evaluated_at"`
+}
+
 // TypeSnapshot is an immutable copy of a registry type at point of use.
 type TypeSnapshot struct {
 	ID          string    `json:"id"`