refactor(ai): convert patrol to agentic tool-based execution

- Replace output-parsing approach with tool-based finding creation
- PatrolService now uses runAIAnalysis with proper scope handling
- Add tool event streaming (tool_start, tool_end) to patrol events
- Expose GetExecutor() on chat.Service for patrol integration
- Remove regex-based finding extraction in favor of patrol tools

The patrol now uses the same agentic loop as chat, with the LLM calling
patrol_report_finding to create findings rather than outputting JSON
that gets parsed. This is more reliable and consistent with the tool model.

internal/ai/chat/service.go

@@ -798,6 +798,14 @@ func (s *Service) GetBaseURL() string {
 	return ""
 }
 
+// GetExecutor returns the underlying tool executor so callers (e.g. patrol)
+// can set session-scoped state like the PatrolFindingCreator before executing.
+func (s *Service) GetExecutor() *tools.PulseToolExecutor {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	return s.executor
+}
+
 // Provider setter methods
 
 func (s *Service) SetAlertProvider(provider MCPAlertProvider) {