fix(windows): GUI subsystem + parent-console attach + canonical muyue.exe (v0.7.5)

Three Windows install/launch issues reported by the user:

1. Double-click on Desktop shortcut → dialog "This is a command line
   tool. You need to open cmd.exe and run it from there."
   Cause: charmbracelet/huh detects no TTY when launched via Explorer
   and aborts. Fix:
   - cmd/muyue/commands/root.go: skip RunFirstTimeSetup when
     os.Stdin is not a character device; persist config.Default()
     and let the React onboarding wizard handle first-run UX.
   - ci-{main,develop}.yml: build Windows binaries with
     -ldflags="-H=windowsgui" so the .exe is a GUI subsystem app —
     no console window flashes on double-click.

2. CLI sub-commands (`muyue scan`, `muyue install-shortcuts`, etc.)
   would lose all output under -H=windowsgui when launched from
   cmd.exe / PowerShell. Mitigation:
   - cmd/muyue/console_windows.go (new, build-tagged): on init(),
     call kernel32!AttachConsole(ATTACH_PARENT_PROCESS). If the
     parent has a console, rebind os.Stdout/os.Stderr/os.Stdin to
     it and call log.SetOutput(os.Stderr) so existing log.Printf
     calls surface. If no parent console (Explorer), exit silently.

3. After install, `muyue` not recognized in PowerShell.
   Causes: (a) the extracted binary is muyue-windows-amd64.exe, not
   muyue.exe; (b) the user PATH update by install-shortcuts doesn't
   propagate to the existing PowerShell session.
   Fix in install-shortcuts:
   - Copy self to <installDir>/muyue.exe (rename impossible — the
     running .exe is locked on Windows) so `muyue` resolves once
     PATH is set.
   - Update Desktop + Start Menu .lnk to target the canonical
     muyue.exe rather than the platform-suffixed binary.
   - Print the line `$env:Path += ';<installDir>'` for the user to
     paste, refreshing the current session immediately.
   - ci-main.yml install snippet bumps to 5 lines, last being
     `$env:Path += ";$dest"`.

- internal/version/version.go: 0.7.4 → 0.7.5
- CHANGELOG.md: v0.7.5 entry covers all three fixes

cmd/muyue/commands/install_shortcuts.go

@@ -2,10 +2,12 @@ package commands
 
 import (
 	"fmt"
+	"io"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"runtime"
+	"strings"
 
 	"github.com/spf13/cobra"
 )
@@ -34,7 +36,20 @@ var installShortcutsCmd = &cobra.Command{
 		installDir := filepath.Dir(exe)
 
 		fmt.Println("Installing Muyue shortcuts...")
-		fmt.Printf("  Executable : %s\n", exe)
+		fmt.Printf("  Source     : %s\n", exe)
+
+		// Provide a clean `muyue.exe` next to the platform-suffixed binary so
+		// users can type `muyue` once the install dir is on PATH. Copy (not
+		// rename) because the running .exe is locked on Windows.
+		canonicalExe := filepath.Join(installDir, "muyue.exe")
+		if !strings.EqualFold(exe, canonicalExe) {
+			if err := copyFile(exe, canonicalExe); err != nil {
+				fmt.Fprintf(os.Stderr, "  Copy       : warning — could not create muyue.exe: %v\n", err)
+				canonicalExe = exe
+			} else {
+				fmt.Printf("  Canonical  : %s\n", canonicalExe)
+			}
+		}
 
 		desktop, err := userShellFolder("Desktop")
 		if err != nil {
@@ -48,12 +63,12 @@ var installShortcutsCmd = &cobra.Command{
 		desktopLnk := filepath.Join(desktop, "Muyue.lnk")
 		startLnk := filepath.Join(startMenu, "Muyue.lnk")
 
-		if err := createWindowsShortcut(desktopLnk, exe, installDir, "Muyue — AI-powered dev environment"); err != nil {
+		if err := createWindowsShortcut(desktopLnk, canonicalExe, installDir, "Muyue — AI-powered dev environment"); err != nil {
 			return fmt.Errorf("create desktop shortcut: %w", err)
 		}
 		fmt.Printf("  Desktop    : %s\n", desktopLnk)
 
-		if err := createWindowsShortcut(startLnk, exe, installDir, "Muyue — AI-powered dev environment"); err != nil {
+		if err := createWindowsShortcut(startLnk, canonicalExe, installDir, "Muyue — AI-powered dev environment"); err != nil {
 			return fmt.Errorf("create Start Menu shortcut: %w", err)
 		}
 		fmt.Printf("  Start Menu : %s\n", startLnk)
@@ -61,14 +76,37 @@ var installShortcutsCmd = &cobra.Command{
 		if err := addUserPATH(installDir); err != nil {
 			fmt.Fprintf(os.Stderr, "  PATH       : warning — could not add %s to user PATH: %v\n", installDir, err)
 		} else {
-			fmt.Printf("  PATH       : added %s (open a new terminal to pick it up)\n", installDir)
+			fmt.Printf("  PATH       : added %s\n", installDir)
 		}
 
 		fmt.Println("\nDone — double-click the Muyue icon on your Desktop to launch.")
+		fmt.Println("\nTo use 'muyue' from this PowerShell session right now, run:")
+		fmt.Printf("  $env:Path += ';%s'\n", installDir)
+		fmt.Println("(New terminals will pick up the user PATH automatically.)")
 		return nil
 	},
 }
 
+// copyFile duplicates src to dst, overwriting an existing dst (used to drop a
+// `muyue.exe` next to the platform-suffixed binary so the command is callable
+// as `muyue` from PATH).
+func copyFile(src, dst string) error {
+	in, err := os.Open(src)
+	if err != nil {
+		return err
+	}
+	defer in.Close()
+	out, err := os.Create(dst)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+	if _, err := io.Copy(out, in); err != nil {
+		return err
+	}
+	return out.Sync()
+}
+
 func init() {
 	rootCmd.AddCommand(installShortcutsCmd)
 }