chore: remove dead code (packages, functions, types, constants)

Remove 5 unused packages (daemon, preview, proxy, workflow) and dead
symbols across 7 files: orchestrator workflow engine, skills Target type
and Update(), LSP config generation, installer SetupPrompt(), unexported
desktop options, and version License/Prerelease. Total: -1453 lines.

internal/orchestrator/orchestrator_test.go

@@ -7,13 +7,6 @@ import (
 	"github.com/muyue/muyue/internal/config"
 )
 
-func testConfig() *config.MuyueConfig {
-	cfg := config.Default()
-	cfg.AI.Providers[0].Active = true
-	cfg.AI.Providers[0].APIKey = "test-api-key-12345"
-	return cfg
-}
-
 func TestCleanAIResponse(t *testing.T) {
 	tests := []struct {
 		name     string
@@ -153,58 +146,3 @@ func TestNewNoAPIKey(t *testing.T) {
 		t.Error("Should fail with no API key")
 	}
 }
-
-func TestHistoryManagement(t *testing.T) {
-	cfg := testConfig()
-	orch, err := New(cfg)
-	if err != nil {
-		t.Fatalf("New failed: %v", err)
-	}
-
-	h := orch.History()
-	if len(h) != 0 {
-		t.Errorf("Expected empty history, got %d", len(h))
-	}
-
-	orch.ClearHistory()
-	h = orch.History()
-	if len(h) != 0 {
-		t.Errorf("Expected 0 after clear, got %d", len(h))
-	}
-}
-
-func TestHistoryCopy(t *testing.T) {
-	cfg := testConfig()
-	orch, _ := New(cfg)
-
-	orch.history = []Message{
-		{Role: "user", Content: "hello"},
-	}
-
-	h := orch.History()
-	h[0].Content = "modified"
-
-	orig := orch.History()
-	if orig[0].Content == "modified" {
-		t.Error("History should return a copy")
-	}
-}
-
-func TestMaxHistorySize(t *testing.T) {
-	cfg := testConfig()
-	orch, _ := New(cfg)
-
-	for i := 0; i < maxHistorySize+10; i++ {
-		orch.histMu.Lock()
-		orch.history = append(orch.history, Message{Role: "user", Content: "msg"})
-		if len(orch.history) > maxHistorySize {
-			orch.history = orch.history[len(orch.history)-maxHistorySize:]
-		}
-		orch.histMu.Unlock()
-	}
-
-	h := orch.History()
-	if len(h) > maxHistorySize {
-		t.Errorf("History should be capped at %d, got %d", maxHistorySize, len(h))
-	}
-}