fix(tests): populate help-parameter vars + commandName in BeforeDiscovery so the param-help check runs

Propagates PowerShellModuleTemplate#35. The 'help parameter help' Context used
-Foreach $helpParameterNames with the variable set only in BeforeAll (run phase).
Pester evaluates -Foreach during DISCOVERY, so the collection was $null then and
the Context expanded to ZERO tests -- the 'no stale/extra parameters documented in
help' check was a silent no-op. Populate $helpParameters/$helpParameterNames (and
$commandName, used in the Context name) in BeforeDiscovery so the check actually runs.

Surgical fix on current main; the broader test-scaffolding alignment (this repo's
open style/align-test-scaffolding-with-template PR) remains separate.

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

Author: tablackburn

tests/Help.tests.ps1

@@ -143,11 +143,16 @@ BeforeAll {
 Describe "Test help for <_.Name>" -ForEach $commands {
 
     BeforeDiscovery {
-        # Get command help, parameters, and links
+        # Get command help, parameters, and links. These are duplicated in BeforeAll
+        # below; they must also exist here because the nested Context blocks use them in
+        # -ForEach, which Pester evaluates during discovery (before BeforeAll runs).
         $command               = $_
+        $commandName           = $command.Name
         $commandHelp           = Get-Help -Name $command.Name -ErrorAction 'SilentlyContinue'
         $commandParameters     = global:FilterOutCommonParameters -Parameters $command.ParameterSets.Parameters
         $commandParameterNames = $commandParameters.Name
+        $helpParameters        = global:FilterOutCommonParameters -Parameters $commandHelp.Parameters.Parameter
+        $helpParameterNames    = $helpParameters.Name
         $helpLinks             = $commandHelp.relatedLinks.navigationLink.uri | Where-Object { $_ -match '^https?://' }
     }