feat: add Gateway page and Runs page with real-time updates

- Implemented a new Gateway page that provides a uniform ingress for deployed agents.
- Created a Runs page that lists recent pipeline executions with auto-refresh and error handling.
- Added a RunsListener component to handle real-time notifications for new runs via SSE.
- Updated the AppSidebar to include links to the new Gateway and Runs pages.
- Enhanced FlowNode component to improve status display and styling.
- Introduced EmptySection component for consistent empty state presentation.
- Updated API utility to include a new endpoint for the runs stream.

pkg/logstore/logstore.go

@@ -0,0 +1,147 @@
+// Package logstore archives per-node execution logs to S3-compatible
+// object storage (MinIO in dev). The API server writes one object per
+// node when the node finishes; the live SSE feed continues to stream
+// during execution.
+//
+// Object key layout:
+//   <bucket>/runs/<execID>/<nodeName>.log
+package logstore
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+	"time"
+
+	"github.com/minio/minio-go/v7"
+	"github.com/minio/minio-go/v7/pkg/credentials"
+)
+
+// Store is the interface the API server uses. Implementations include the
+// MinIO/S3-backed Mongo (mongo) store and a memory store for tests.
+type Store interface {
+	Put(ctx context.Context, execID, node string, data []byte) error
+	Get(ctx context.Context, execID, node string) (io.ReadCloser, error)
+	Exists(ctx context.Context, execID, node string) (bool, error)
+}
+
+// ErrNotFound is returned by Get when the object doesn't exist.
+var ErrNotFound = errors.New("log not found")
+
+// Config carries connection details for a MinIO/S3 endpoint.
+type Config struct {
+	Endpoint  string // host:port, no scheme — e.g. "minio:9000" or "127.0.0.1:9000"
+	AccessKey string
+	SecretKey string
+	Bucket    string
+	UseSSL    bool
+}
+
+// Minio is the production Store implementation, backed by minio-go.
+type Minio struct {
+	cli    *minio.Client
+	bucket string
+}
+
+// NewMinio dials the endpoint with a 10s timeout and ensures the bucket
+// exists. Returns an error if either step fails.
+func NewMinio(ctx context.Context, cfg Config) (*Minio, error) {
+	if cfg.Endpoint == "" {
+		return nil, errors.New("MINIO_ENDPOINT is required")
+	}
+	if cfg.Bucket == "" {
+		cfg.Bucket = "flow-logs"
+	}
+	cli, err := minio.New(cfg.Endpoint, &minio.Options{
+		Creds:  credentials.NewStaticV4(cfg.AccessKey, cfg.SecretKey, ""),
+		Secure: cfg.UseSSL,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("minio client: %w", err)
+	}
+
+	bucketCtx, cancel := context.WithTimeout(ctx, 10*time.Second)
+	defer cancel()
+	exists, err := cli.BucketExists(bucketCtx, cfg.Bucket)
+	if err != nil {
+		return nil, fmt.Errorf("minio bucket check %q: %w", cfg.Bucket, err)
+	}
+	if !exists {
+		if err := cli.MakeBucket(bucketCtx, cfg.Bucket, minio.MakeBucketOptions{}); err != nil {
+			return nil, fmt.Errorf("minio make bucket %q: %w", cfg.Bucket, err)
+		}
+	}
+	return &Minio{cli: cli, bucket: cfg.Bucket}, nil
+}
+
+func (m *Minio) Put(ctx context.Context, execID, node string, data []byte) error {
+	if execID == "" || node == "" {
+		return errors.New("execID and node required")
+	}
+	key := keyFor(execID, node)
+	_, err := m.cli.PutObject(ctx, m.bucket, key,
+		bytes.NewReader(data), int64(len(data)),
+		minio.PutObjectOptions{ContentType: "text/plain; charset=utf-8"})
+	return err
+}
+
+func (m *Minio) Get(ctx context.Context, execID, node string) (io.ReadCloser, error) {
+	key := keyFor(execID, node)
+	obj, err := m.cli.GetObject(ctx, m.bucket, key, minio.GetObjectOptions{})
+	if err != nil {
+		return nil, err
+	}
+	// minio-go returns a lazy *Object; calling Stat surfaces NoSuchKey.
+	if _, err := obj.Stat(); err != nil {
+		_ = obj.Close()
+		var er minio.ErrorResponse
+		if errors.As(err, &er) && er.Code == "NoSuchKey" {
+			return nil, ErrNotFound
+		}
+		return nil, err
+	}
+	return obj, nil
+}
+
+func (m *Minio) Exists(ctx context.Context, execID, node string) (bool, error) {
+	key := keyFor(execID, node)
+	_, err := m.cli.StatObject(ctx, m.bucket, key, minio.StatObjectOptions{})
+	if err == nil {
+		return true, nil
+	}
+	var er minio.ErrorResponse
+	if errors.As(err, &er) && er.Code == "NoSuchKey" {
+		return false, nil
+	}
+	return false, err
+}
+
+// keyFor returns the object key for a given execution+node pair. We sanitise
+// the node name so weird characters (slashes, spaces) don't bork S3 keys.
+func keyFor(execID, node string) string {
+	return "runs/" + execID + "/" + sanitize(node) + ".log"
+}
+
+func sanitize(s string) string {
+	// Replace anything that isn't alnum/-/_ with "-".
+	var b strings.Builder
+	for _, r := range s {
+		switch {
+		case r >= 'a' && r <= 'z',
+			r >= 'A' && r <= 'Z',
+			r >= '0' && r <= '9',
+			r == '-', r == '_', r == '.':
+			b.WriteRune(r)
+		default:
+			b.WriteRune('-')
+		}
+	}
+	out := b.String()
+	if out == "" {
+		out = "node"
+	}
+	return out
+}