feat: build automation rules audit trail

[Junman140]

Closes #563

Implements the automation rules audit trail:

• Adds automation_rules, automation_rule_versions, and automation_rule_executions tables
• Creates AutomationRulesService with versioned snapshots and actor tracking
• Extends rule_evaluator_logs with executed_by, execution_context, and metadata
• Exposes CRUD, history, search, and CSV export endpoints under /api/v1/automation-rules
• Integrates rule lifecycle events with the central audit_logs table
• Adds unit tests and documentation