Rename Pester.ps1 script-scope helper to Pester.ScriptScope.ps1

[nohwnd]

Problem

Installing Pester with Install-PSResource Pester prints a spurious warning:

WARNING: The installation path for the script does not currently appear in the CurrentUser path environment variable. To make the script discoverable, add the script installation path, .../Modules, to the environment PATH variable.

Root cause

PSResourceGet decides whether an installed package is a script by checking for a <ModuleName>.ps1 file in the package root (InstallHelper.cs):

var scriptPath = Path.Combine(tempDirNameVersion, pkgName + PSScriptFileExt); // Pester.ps1
bool isScript = File.Exists(scriptPath);                                       // true!

Pester ships a tiny Pester.ps1 (used by Invoke-InNewScriptScope for script-scope isolation), so isScript becomes true and the PATH warning at if (!_savePkg && isScript) fires. The upstream fix in PSResourceGet#1043 wasn't accepted, so the agreed fallback is to rename the file on Pester's side.

Fix

Rename src/Pester.ps1 → src/Pester.ScriptScope.ps1 so the shipped module no longer contains a file matching the module name, and update its references:

• src/Pester.Runtime.ps1 — the Invoke-InNewScriptScope path
• build.ps1 — the copy-to-bin/ step
• publish/filesToPublish.ps1 — the published-file list

The file must stay a standalone .ps1 on disk (it is invoked as a real script to push a new script scope; it is not inlined into Pester.psm1). A comment in the file and at the call site documents why it must not be named Pester.ps1.

Regression test

Added a StyleRules-tagged test in tst/Pester.Tests.ps1 asserting the built module ships Pester.ScriptScope.ps1 and contains no Pester.ps1.

Verification

• Clean build succeeds; bin/ ships Pester.ScriptScope.ps1 and no Pester.ps1.
• New regression tests pass.
• Running a real test file exercises Invoke-InNewScriptScope and passes (script scope pushed, $PSCommandPath set).
• RSpec acceptance suite: 116/116 passing.
• Custom build-analyzer rules on ./src: no new violations (new file is clean).

Fix #2826