Resolve PowerShell lint errors and enable CI enforcement

[flanakin]

🛠️ Description

This PR fixes all 12 PowerShell lint errors and adds configuration to prevent future issues. It also fixes a critical CI issue where lint/unit test failures were not actually failing the GitHub Action.

Lint fixes:

• Trailing whitespace: Invoke-Rest.ps1, Save-FinOpsHubTemplate.ps1, Start-FinOpsCostExport.ps1
• UTF-8 BOM encoding: Get-FinOpsCostExport.ps1, Remove-FinOpsCostExport.ps1, Start-FinOpsCostExport.ps1
• OutputType mismatch: Split-AzureResourceId.ps1 - return type changed from @{} to [AzureResourceIdInfo]@{}
• ShouldProcess: Initialize-FinOpsHubDeployment.ps1, New-FinOpsCostExport.ps1, Start-FinOpsCostExport.ps1
• Write-Host usage: Remove-FinOpsHub.ps1 - changed to Write-Information
• Global variable: Initialize-Tests.ps1 - refactored to use Get-FinOpsHubRequiredResourceProvider function

Configuration improvements:

• .editorconfig: Added charset = utf-8-bom for .ps1, .psm1, .psd1 files
• .vscode/settings.json: Added files.encoding: utf8bom and files.trimTrailingWhitespace: true for PowerShell

CI fix:

• .build/BuildHelper/Start-PesterTest.ps1: Added $pesterArgs.Run.Exit = $true so Pester returns non-zero exit code on test failures, which will now fail the GitHub Action

📋 Checklist

🔬 How did you test this change?

• 🤏 Lint tests
• 🤞 PS -WhatIf / az validate
• 👍 Manually deployed + verified
• 💪 Unit tests
• 🙌 Integration tests

🙋‍♀️ Do any of the following that apply?

• 🚨 This is a breaking change.
• 🤏 The change is less than 20 lines of code.

📑 Did you update docs/changelog.md?

• ✅ Updated changelog (required for dev PRs)
• ➡️ Will add log in a future PR (feature branch PRs only)
• ❎ Log not needed (small/internal change)

📖 Did you update documentation?

• ✅ Public docs in docs (required for dev)
• ✅ Public docs in docs-mslearn (required for dev)
• ✅ Internal dev docs in docs-wiki (required for dev)
• ✅ Internal dev docs in src (required for dev)
• ➡️ Will add docs in a future PR (feature branch PRs only)
• ❎ Docs not needed (small/internal change)

---

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR targets PowerShell code quality and CI reliability in the FinOps toolkit by resolving PowerShell lint issues (formatting/encoding and PSScriptAnalyzer rules) and ensuring test failures correctly fail the build.

Changes:

• Updated several PowerShell cmdlets to align with lint rules (ShouldProcess support, OutputType consistency, and replacing Write-Host usage).
• Normalized PowerShell file encoding/whitespace handling via .editorconfig and VS Code workspace settings.
• Fixed CI/Pester invocation so failed tests produce a non-zero exit code.

Reviewed changes

Copilot reviewed 14 out of 16 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/powershell/Tests/Unit/New-FinOpsCostExport.Tests.ps1	Updates assertions for trimmed default storage path behavior.
src/powershell/Tests/Unit/Deploy-FinOpsHub.Tests.ps1	Improves mocks to match actual function calls/signatures.
src/powershell/Tests/Integration/Hubs.Tests.ps1	Removes dependency on a global variable; uses helper function instead.
src/powershell/Tests/Initialize-Tests.ps1	Replaces a global test variable with a helper function returning required RPs.
src/powershell/Public/Start-FinOpsCostExport.ps1	Adds SupportsShouldProcess handling and formatting fixes.
src/powershell/Public/Remove-FinOpsHub.ps1	Replaces Write-Host with Write-Information for deletion output.
src/powershell/Public/Remove-FinOpsCostExport.ps1	Updates file encoding (BOM).
src/powershell/Public/New-FinOpsCostExport.ps1	Adds SupportsShouldProcess and gates creation/run behavior under ShouldProcess.
src/powershell/Public/Initialize-FinOpsHubDeployment.ps1	Wraps provider registration call behind ShouldProcess.
src/powershell/Public/Get-FinOpsCostExport.ps1	Updates file encoding (BOM).
src/powershell/Private/Split-AzureResourceId.ps1	Adjusts return type to match declared OutputType.
src/powershell/Private/Save-FinOpsHubTemplate.ps1	Trims whitespace-only line.
src/powershell/Private/Invoke-Rest.ps1	Removes trailing whitespace.
.vscode/settings.json	Enforces PowerShell encoding and trimming behavior in VS Code.
.editorconfig	Sets PowerShell file charset to UTF-8 BOM and standardizes indentation.
.build/BuildHelper/Start-PesterTest.ps1	Ensures Pester exits non-zero on test failures (Run.Exit = $true).

[flanakin]

🤖 [AI][Claude] PR Update Summary

Addressed: 5 thread(s)

• ✅ Implemented: 4
• 🤔 Needs discussion: 1

Changes:

• Removed unreachable dead code in Split-AzureResourceId.ps1
• Fixed inverted verbose logging in Start-FinOpsCostExport.ps1
• Wrapped Register-AzResourceProvider in ShouldProcess in New-FinOpsCostExport.ps1
• Added changelog entry for user-facing fixes

Discussion: Write-Information in Remove-FinOpsHub.ps1 is intentional per PowerShell best practices (replacing Write-Host lint violation).

[flanakin]

The 2 failing checks are resolved by PR #2021