* fix(launcher): hide console flashes in all Windows child processes
PR #2654 only applied HideWindow to child processes in gateway.go (powershell, tasklist, ps). Several other files still use exec.Command directly, causing visible console windows on Windows.
- startup.go: reg query/add/delete for autostart registry
- version.go: picoclaw version subcommand
- runtime.go: rundll32 for browser launch
- onboard.go: picoclaw onboard subcommand
Add launcherExecCommand to the utils package (matching the api package pattern) and replace all bare exec.Command calls on Windows paths.
* refactor: consolidate launcherExecCommand into utils package
Export LauncherExecCommand and ApplyLauncherProcAttrs from the utils
package as the single source of truth. The api package now imports
and delegates to these exported functions, eliminating code duplication.
Addresses review feedback from imguoguo on PR #3061.