fix(windows): suppress console popup on child_process calls (#498)

On Windows, v0.9.5's detached shared daemon (#411) has no inherited console,
so any console-subsystem child it spawns gets a fresh visible console window
unless the spawn passes `windowsHide: true`. The fix adds the flag to all
ten `spawnSync` / `execFileSync` / `execSync` call sites across extraction,
sync, installer, and the WASM-flags relaunch. macOS/Linux ignore the option,
so this is a no-op elsewhere.

Fixes #485, #510, #530.

Co-authored work:
- #498 (csw-chen) — full sweep across extraction, sync, installer, and wasm-runtime. **This is the change being merged.**
- #505 (yushengruohui) — independently identified and fixed the 7 git execFileSync sites. Superseded by #498's broader sweep; same diagnosis.
- #521 (JirA44) — independently identified and fixed the WASM-runtime spawnSync re-exec. Superseded by #498's broader sweep; same diagnosis.

Validated on Windows 11 ARM64 (Parallels): a detached parent's 15 git spawns produce 15 visible black flash-windows without the fix and 0 with it.

src/extraction/index.ts

@@ -191,7 +191,7 @@ export function buildDefaultIgnore(rootDir: string): Ignore {
  * (See issue #193.)
  */
 function collectGitFiles(repoDir: string, prefix: string, files: Set<string>): void {
-  const gitOpts = { cwd: repoDir, encoding: 'utf-8' as const, timeout: 30000, maxBuffer: 50 * 1024 * 1024, stdio: ['pipe', 'pipe', 'pipe'] as ['pipe', 'pipe', 'pipe'] };
+  const gitOpts = { cwd: repoDir, encoding: 'utf-8' as const, timeout: 30000, maxBuffer: 50 * 1024 * 1024, stdio: ['pipe', 'pipe', 'pipe'] as ['pipe', 'pipe', 'pipe'], windowsHide: true };
 
   // Tracked files. --recurse-submodules pulls in files from active submodules,
   // which the index would otherwise represent only as a commit pointer.
@@ -241,7 +241,7 @@ function getGitVisibleFiles(rootDir: string): Set<string> | null {
     const gitRoot = execFileSync(
       'git',
       ['rev-parse', '--show-toplevel'],
-      { cwd: rootDir, encoding: 'utf-8', timeout: 5000, stdio: ['pipe', 'pipe', 'pipe'] }
+      { cwd: rootDir, encoding: 'utf-8', timeout: 5000, stdio: ['pipe', 'pipe', 'pipe'], windowsHide: true }
     ).trim();
 
     if (path.resolve(gitRoot) !== path.resolve(rootDir)) {
@@ -250,7 +250,7 @@ function getGitVisibleFiles(rootDir: string): Set<string> | null {
         execFileSync(
           'git',
           ['check-ignore', '-q', path.resolve(rootDir)],
-          { cwd: rootDir, encoding: 'utf-8', timeout: 5000, stdio: ['pipe', 'pipe', 'pipe'] }
+          { cwd: rootDir, encoding: 'utf-8', timeout: 5000, stdio: ['pipe', 'pipe', 'pipe'], windowsHide: true }
         );
         // Directory is gitignored by parent repo — fall back to filesystem walk
         return null;
@@ -291,7 +291,7 @@ function getGitChangedFiles(rootDir: string): GitChanges | null {
     const output = execFileSync(
       'git',
       ['status', '--porcelain', '--no-renames'],
-      { cwd: rootDir, encoding: 'utf-8', timeout: 10000, stdio: ['pipe', 'pipe', 'pipe'] }
+      { cwd: rootDir, encoding: 'utf-8', timeout: 10000, stdio: ['pipe', 'pipe', 'pipe'], windowsHide: true }
     );
 
     const modified: string[] = [];

src/extraction/wasm-runtime-flags.ts

@@ -98,6 +98,7 @@ export function relaunchWithWasmRuntimeFlagsIfNeeded(scriptPath: string): void {
   const result = spawnSync(process.execPath, argv, {
     stdio: 'inherit',
     env: { ...process.env, [RELAUNCH_GUARD_ENV]: '1', [HOST_PPID_ENV]: String(process.ppid) },
+    windowsHide: true,
   });
 
   if (result.error) {