refactor: simplify architecture and harden lifecycle

Remove obsolete implementations, centralize background task ownership and terminal-state recovery, consolidate frontend routing and log streaming, and enforce project-wide verification in CI.

server/internal/lifecycle/supervisor_test.go

@@ -0,0 +1,54 @@
+package lifecycle
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"time"
+)
+
+func TestSupervisorShutdownCancelsAndWaits(t *testing.T) {
+	supervisor := NewSupervisor(context.Background())
+	started := make(chan struct{})
+	finished := make(chan struct{})
+	if !supervisor.Go(func(ctx context.Context) {
+		close(started)
+		<-ctx.Done()
+		close(finished)
+	}) {
+		t.Fatal("expected task to be accepted")
+	}
+	<-started
+
+	waitCtx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+	if err := supervisor.Shutdown(waitCtx); err != nil {
+		t.Fatalf("Shutdown returned error: %v", err)
+	}
+	select {
+	case <-finished:
+	default:
+		t.Fatal("Shutdown returned before the task finished")
+	}
+	if supervisor.Go(func(context.Context) {}) {
+		t.Fatal("expected task submitted after shutdown to be rejected")
+	}
+}
+
+func TestSupervisorShutdownHonorsWaitContext(t *testing.T) {
+	supervisor := NewSupervisor(context.Background())
+	release := make(chan struct{})
+	if !supervisor.Go(func(context.Context) { <-release }) {
+		t.Fatal("expected task to be accepted")
+	}
+
+	waitCtx, cancel := context.WithCancel(context.Background())
+	cancel()
+	if err := supervisor.Shutdown(waitCtx); !errors.Is(err, context.Canceled) {
+		t.Fatalf("Shutdown error = %v, want context.Canceled", err)
+	}
+	close(release)
+	if err := supervisor.Shutdown(context.Background()); err != nil {
+		t.Fatalf("second Shutdown returned error: %v", err)
+	}
+}