feat: migrate to typed messages

- Switch OnMessage → OnTypedMessage with natsutil.Decode[messages.PipelineTrigger]
- Return *messages.PipelineStatus (not map[string]any)
- Remove strVal/mapVal helpers
- Add .dockerignore, GOAMD64=v3 in Dockerfile
- Update tests for typed structs (14 tests pass)

e2e_test.go

@@ -6,6 +6,8 @@ import (
 	"net/http/httptest"
 	"sync/atomic"
 	"testing"
+
+	"git.daviestechlabs.io/daviestechlabs/handler-base/messages"
 )
 
 // ────────────────────────────────────────────────────────────────────────────
@@ -117,34 +119,28 @@ func TestPipelineDispatchE2E_AllEngines(t *testing.T) {
 }
 
 func TestPipelineDispatchE2E_UnknownPipeline(t *testing.T) {
-	// Simulate what main.go's OnMessage does for unknown pipeline
-	data := map[string]any{
-		"request_id": "req-bad",
-		"pipeline":   "nonexistent-pipeline",
-	}
-
-	pipelineName := strVal(data, "pipeline", "")
+	// Verify unknown pipeline is rejected and available list is provided
+	pipelineName := "nonexistent-pipeline"
 	_, ok := pipelines[pipelineName]
 	if ok {
 		t.Error("nonexistent pipeline should not be found")
 	}
 
-	// Build error response like main.go
 	names := make([]string, 0, len(pipelines))
 	for k := range pipelines {
 		names = append(names, k)
 	}
-	resp := map[string]any{
-		"request_id":          strVal(data, "request_id", ""),
-		"status":              "error",
-		"error":               "Unknown pipeline: nonexistent-pipeline",
-		"available_pipelines": names,
+	resp := &messages.PipelineStatus{
+		RequestID:          "req-bad",
+		Status:             "error",
+		Error:              "Unknown pipeline: nonexistent-pipeline",
+		AvailablePipelines: names,
 	}
 
-	if resp["status"] != "error" {
+	if resp.Status != "error" {
 		t.Error("expected error status")
 	}
-	if len(resp["available_pipelines"].([]string)) != len(pipelines) {
+	if len(resp.AvailablePipelines) != len(pipelines) {
 		t.Errorf("available_pipelines count mismatch")
 	}
 }