🩹 [Patch]: Encode all PowerShell files using UTF8 with BOM (#231)

## Description

This pull request updates several PowerShell script files across the
project. The main change is the addition of a Unicode Byte Order Mark
(BOM) at the beginning of each file, which can help ensure proper
encoding and compatibility, especially on Windows systems. No functional
code changes have been made.

Author: MariusStorhaug

.specify/scripts/powershell/check-prerequisites.ps1

@@ -1,4 +1,4 @@
-#!/usr/bin/env pwsh
+#!/usr/bin/env pwsh
 
 # Consolidated prerequisite checking script (PowerShell)
 #

.specify/scripts/powershell/common.ps1

@@ -1,4 +1,4 @@
-#!/usr/bin/env pwsh
+#!/usr/bin/env pwsh
 # Common PowerShell functions analogous to common.sh
 
 function Get-RepoRoot {

.specify/scripts/powershell/create-new-feature.ps1

@@ -1,4 +1,4 @@
-#!/usr/bin/env pwsh
+#!/usr/bin/env pwsh
 # Create a new feature
 [CmdletBinding()]
 param(

.specify/scripts/powershell/setup-plan.ps1

@@ -1,4 +1,4 @@
-#!/usr/bin/env pwsh
+#!/usr/bin/env pwsh
 # Setup implementation plan for a feature
 
 [CmdletBinding()]

.specify/scripts/powershell/update-agent-context.ps1

@@ -1,4 +1,4 @@
-#!/usr/bin/env pwsh
+#!/usr/bin/env pwsh
 <#!
 .SYNOPSIS
 Update agent context files with information from plan.md (PowerShell version)

tests/srcTestRepo/src/variables/public/Planets.ps1

@@ -1,4 +1,4 @@
-$script:Planets = @(
+$script:Planets = @(
     @{
         Name      = 'Mercury'
         Mass      = 0.330

tests/srcTestRepo/tests/AfterAll.ps1

@@ -1,4 +1,4 @@
-Write-Warning "=== AFTERALL TEARDOWN SCRIPT EXECUTING ==="
+Write-Warning "=== AFTERALL TEARDOWN SCRIPT EXECUTING ==="
 Write-Warning "Tearing down test environment..."
 
 # Example teardown tasks:

tests/srcTestRepo/tests/BeforeAll.ps1

@@ -1,4 +1,4 @@
-Write-Warning "=== BEFOREALL SETUP SCRIPT EXECUTING ==="
+Write-Warning "=== BEFOREALL SETUP SCRIPT EXECUTING ==="
 Write-Warning "Setting up test environment..."
 
 # Example setup tasks:

tests/srcWithManifestTestRepo/src/variables/public/Planets.ps1

@@ -1,4 +1,4 @@
-$script:Planets = @(
+$script:Planets = @(
     @{
         Name      = 'Mercury'
         Mass      = 0.330

tests/srcWithManifestTestRepo/tests/AfterAll.ps1

@@ -1,4 +1,4 @@
-Write-Warning "=== AFTERALL TEARDOWN SCRIPT (Environments) EXECUTING ==="
+Write-Warning "=== AFTERALL TEARDOWN SCRIPT (Environments) EXECUTING ==="
 Write-Warning "Tearing down test environment for Environments..."
 
 # Example teardown tasks for Environments directory: