refactor(build): drop $_ prefix from helper variable names (#20)

Rename $_moduleVersion → $moduleVersion and $_stagedOutput → $stagedOutput
in build.psake.ps1's properties block. Pure rename, no behavior change.

The $_ prefix was meant to signal "internal helper, not configuration"
but is easy to misread as the $_ automatic pipeline variable. The
shorter names are clearer in context (assignment targets in a
properties{} block, not script-block parameters).

Same rename applied across the user's downstream modules
(JsmOperations, PlexAutomationToolkit, ReScenePS) so the template and
all initialized modules stay in sync.

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

Author: tablackburn

build.psake.ps1

@@ -22,11 +22,11 @@ properties {
     if (-not $Env:BHPSModuleManifest -or -not $Env:BHProjectName) {
         throw 'Coverage configuration requires BuildHelpers env vars. Run via ./build.ps1 or call Set-BuildEnvironment first.'
     }
-    $_moduleVersion = (Import-PowerShellDataFile -Path $Env:BHPSModuleManifest).ModuleVersion
-    $_stagedOutput = [IO.Path]::Combine($PSScriptRoot, 'Output', $Env:BHProjectName, $_moduleVersion)
+    $moduleVersion = (Import-PowerShellDataFile -Path $Env:BHPSModuleManifest).ModuleVersion
+    $stagedOutput = [IO.Path]::Combine($PSScriptRoot, 'Output', $Env:BHProjectName, $moduleVersion)
     $PSBPreference.Test.CodeCoverage.Files = @(
-        "$_stagedOutput/Public/*.ps1"
-        "$_stagedOutput/Private/*.ps1"
+        "$stagedOutput/Public/*.ps1"
+        "$stagedOutput/Private/*.ps1"
     )
     $PSBPreference.Test.CodeCoverage.Threshold = 0  # Threshold enforced by Codecov
     $PSBPreference.Test.CodeCoverage.OutputFile = [IO.Path]::Combine($PSScriptRoot, 'out', 'codeCoverage.xml')