feat(audit): Phase 3 - Integrate audit logging with tools registry

Add audit logging to ExecuteWithContext:
- Log all tool executions with args, result, duration
- Log tool not found errors
- Include channel context for request tracing
- Works alongside existing structured logging

The audit logs capture:
- Tool name and ID
- Arguments (JSON-serializable)
- Result content
- Error status and async status
- Execution duration in milliseconds

pkg/tools/registry.go

@@ -7,6 +7,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/sipeed/picoclaw/pkg/audit"
 	"github.com/sipeed/picoclaw/pkg/logger"
 	"github.com/sipeed/picoclaw/pkg/providers"
 )
@@ -61,6 +62,8 @@ func (r *ToolRegistry) ExecuteWithContext(
 			map[string]any{
 				"tool": name,
 			})
+		// Audit the error
+		audit.LogError(ctx, "tool_not_found", fmt.Sprintf("tool %q not found", name), true)
 		return ErrorResult(fmt.Sprintf("tool %q not found", name)).WithError(fmt.Errorf("tool not found"))
 	}
 
@@ -105,6 +108,17 @@ func (r *ToolRegistry) ExecuteWithContext(
 			})
 	}
 
+	// Audit logging
+	ctx = audit.WithChannelContext(ctx, channel, chatID, "")
+	audit.LogToolCall(ctx, &audit.ToolCallData{
+		ToolID:    name,
+		Name:      name,
+		Arguments: args,
+		Result:    result.ForLLM,
+		IsError:   result.IsError,
+		IsAsync:   result.Async,
+	}, duration.Milliseconds())
+
 	return result
 }