fix: Add proper WebSocket compatibility shim for test imports

Updated api/ws_compat.go to properly delegate to api/ws package:
- NewWSHandler returns http.Handler interface (not interface{})
- All Opcode* constants re-exported from ws package
- Maintains backward compatibility for existing tests

This allows gradual migration of tests to use api/ws directly without
breaking the build. Tests can be updated incrementally.

Build status: Compiles successfully

internal/api/ws_compat.go

@@ -0,0 +1,64 @@
+package api
+
+import (
+	"net/http"
+
+	"github.com/jfraeys/fetch_ml/internal/api/ws"
+	"github.com/jfraeys/fetch_ml/internal/audit"
+	"github.com/jfraeys/fetch_ml/internal/auth"
+	"github.com/jfraeys/fetch_ml/internal/config"
+	"github.com/jfraeys/fetch_ml/internal/experiment"
+	"github.com/jfraeys/fetch_ml/internal/jupyter"
+	"github.com/jfraeys/fetch_ml/internal/logging"
+	"github.com/jfraeys/fetch_ml/internal/queue"
+	"github.com/jfraeys/fetch_ml/internal/storage"
+)
+
+// Re-export WebSocket types from ws package for backward compatibility
+// Deprecated: Use api/ws package directly
+
+// NewWSHandler creates a new WebSocket handler (re-export from ws package)
+// Deprecated: Use ws.NewHandler instead
+func NewWSHandler(
+	authConfig *auth.Config,
+	logger *logging.Logger,
+	expManager *experiment.Manager,
+	dataDir string,
+	taskQueue queue.Backend,
+	db *storage.DB,
+	jupyterServiceMgr *jupyter.ServiceManager,
+	securityCfg *config.SecurityConfig,
+	auditLogger *audit.Logger,
+) http.Handler {
+	return ws.NewHandler(authConfig, logger, expManager, dataDir, taskQueue, db, jupyterServiceMgr, securityCfg, auditLogger)
+}
+
+// WebSocket opcodes (re-exported from ws package)
+// Deprecated: Use ws package constants directly
+const (
+	OpcodeQueueJob             = ws.OpcodeQueueJob
+	OpcodeStatusRequest        = ws.OpcodeStatusRequest
+	OpcodeCancelJob            = ws.OpcodeCancelJob
+	OpcodePrune                = ws.OpcodePrune
+	OpcodeDatasetList          = ws.OpcodeDatasetList
+	OpcodeDatasetRegister      = ws.OpcodeDatasetRegister
+	OpcodeDatasetInfo          = ws.OpcodeDatasetInfo
+	OpcodeDatasetSearch        = ws.OpcodeDatasetSearch
+	OpcodeLogMetric            = ws.OpcodeLogMetric
+	OpcodeGetExperiment        = ws.OpcodeGetExperiment
+	OpcodeQueueJobWithTracking = ws.OpcodeQueueJobWithTracking
+	OpcodeQueueJobWithSnapshot = ws.OpcodeQueueJobWithSnapshot
+	OpcodeQueueJobWithArgs     = ws.OpcodeQueueJobWithArgs
+	OpcodeQueueJobWithNote     = ws.OpcodeQueueJobWithNote
+	OpcodeAnnotateRun          = ws.OpcodeAnnotateRun
+	OpcodeSetRunNarrative      = ws.OpcodeSetRunNarrative
+	OpcodeStartJupyter         = ws.OpcodeStartJupyter
+	OpcodeStopJupyter          = ws.OpcodeStopJupyter
+	OpcodeRemoveJupyter        = ws.OpcodeRemoveJupyter
+	OpcodeRestoreJupyter       = ws.OpcodeRestoreJupyter
+	OpcodeListJupyter          = ws.OpcodeListJupyter
+	OpcodeListJupyterPackages  = ws.OpcodeListJupyterPackages
+	OpcodeValidateRequest      = ws.OpcodeValidateRequest
+	OpcodeGetLogs              = ws.OpcodeGetLogs
+	OpcodeStreamLogs           = ws.OpcodeStreamLogs
+)