Replace em-dashes in PowerShell scripts with ASCII hyphens

PowerShell 5.1 reads .ps1 files as the local ANSI codepage by default,
so non-ASCII characters get garbled. An em-dash inside a string literal
broke install-service.ps1 with a parser error. Sticking to ASCII in
script source avoids the entire class of issue.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/dev-launch.ps1

@@ -4,7 +4,7 @@
     pointing at an isolated data root so production %ProgramData% is not touched.
 
 .DESCRIPTION
-    MUST be run from an elevated PowerShell — the admin pipe is ACL'd to SYSTEM
+    MUST be run from an elevated PowerShell - the admin pipe is ACL'd to SYSTEM
     and the Administrators group, and a non-elevated process cannot connect.
 #>
 [CmdletBinding()]