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/version/version_test.go

@@ -15,28 +15,6 @@ func TestFullVersion(t *testing.T) {
 	}
 }
 
-func TestFullVersionWithPrerelease(t *testing.T) {
-	original := Prerelease
-	Prerelease = "beta.1"
-	defer func() { Prerelease = original }()
-
-	v := FullVersion()
-	if !strings.Contains(v, "beta.1") {
-		t.Errorf("FullVersion should contain prerelease suffix, got %s", v)
-	}
-}
-
-func TestFullVersionWithoutPrerelease(t *testing.T) {
-	original := Prerelease
-	Prerelease = ""
-	defer func() { Prerelease = original }()
-
-	v := FullVersion()
-	if strings.Contains(v, "-") {
-		t.Errorf("FullVersion should not contain prerelease suffix, got %s", v)
-	}
-}
-
 func TestConstants(t *testing.T) {
 	if Name == "" {
 		t.Error("Name should not be empty")
@@ -47,7 +25,4 @@ func TestConstants(t *testing.T) {
 	if Author == "" {
 		t.Error("Author should not be empty")
 	}
-	if License == "" {
-		t.Error("License should not be empty")
-	}
 }