[ENHANCEMENT] Pass Context down when using Visitor for EventSummary

[jcscottiii]

When parsing the EventSummary, we don't pass down the context which could be helpful when shutting down the service to cancel outstanding requests to things like the database.

webstatus.dev/lib/workertypes/types.go

Lines 75 to 106 in b508c57

	// SummaryVisitor defines the contract for consuming immutable Event Summaries.
	// Unlike state blobs which are migrated to the latest schema, summaries are
	// historical records that should be rendered as-is. The Visitor pattern forces
	// consumers to explicitly handle each schema version (e.g. V1, V2) independently.
	type SummaryVisitor interface {
	VisitV1(s EventSummary) error
	}
	// ParseEventSummary handles the version detection and dispatching logic.
	// Consumers (like the Delivery Worker) should use this instead of raw json.Unmarshal.
	func ParseEventSummary(data []byte, v SummaryVisitor) error {
	// 1. Peek at version
	var header struct {
	SchemaVersion string `json:"schemaVersion"`
	}
	if err := json.Unmarshal(data, &header); err != nil {
	return fmt.Errorf("invalid summary json: %w", err)
	}
	// 2. Dispatch
	switch header.SchemaVersion {
	case VersionEventSummaryV1:
	var s EventSummary
	if err := json.Unmarshal(data, &s); err != nil {
	return fmt.Errorf("failed to parse v1 summary: %w", err)
	}
	return v.VisitV1(s)
	default:
	return fmt.Errorf("unknown summary version: %q", header.SchemaVersion)
	}
	}

We should pass the context down