Replace null-coalescing operators with PS5.1-compatible syntax (#443)

Plaster v2.0.0-alpha uses the null-coalescing operator (`??`) introduced
in PowerShell 7.0, breaking compatibility with PowerShell 5.1 as
specified in the module manifest.

## Changes

**Write-PlasterLog.ps1**
- Replaced `??` operators with conditional expressions compatible with
PS5.1+

```powershell
# Before
$currentLogLevel = $script:LogLevel ?? 'Information'
$currentLevelValue = $logLevels[$currentLogLevel] ?? 2

# After
$currentLogLevel = if ($null -ne $script:LogLevel) { $script:LogLevel } else { 'Information' }
$currentLevelValue = if ($null -ne $logLevels[$currentLogLevel]) { $logLevels[$currentLogLevel] } else { 2 }
```

**Plaster.psm1**
- Added dot-sourcing for Private and Public function files
- Implemented selective export of public functions only

> [!WARNING]
>
> <details>
> <summary>Firewall rules blocked me from connecting to one or more
addresses (expand for details)</summary>
>
> #### I tried to connect to the following addresses, but was blocked by
firewall rules:
>
> - `www.powershellgallery.com`
> - Triggering command: `/usr/bin/pwsh pwsh -NoProfile -File ./build.ps1
-Bootstrap` (dns block)
>   - Triggering command: `/usr/bin/pwsh pwsh -NoProfile -Command 
Register-PSRepository -Default -ErrorAction SilentlyContinue
Get-PSRepository` (dns block)
>
> If you need me to access, download, or install something from one of
these locations, you can either:
>
> - Configure [Actions setup
steps](https://gh.io/copilot/actions-setup-steps) to set up my
environment, which run before the firewall is enabled
> - Add the appropriate URLs or hosts to the custom allowlist in this
repository's [Copilot coding agent
settings](https://github.com/PowerShellOrg/Plaster/settings/copilot/coding_agent)
(admins only)
>
> </details>

<!-- START COPILOT ORIGINAL PROMPT -->



<details>

<summary>Original prompt</summary>

> 
> ----
> 
> *This section details on the original issue you should resolve*
> 
> <issue_title>Plaster v2.0.0-alpha broken on Windows</issue_title>
> <issue_description>Hiya,
> 
> [Sampler]() uses Plaster and we've noticed on our pipelines that the
prerelease version breaks on windows because `Write-PlasterLog` uses the
Null-coalescing operator.
> 
>
https://github.com/PowerShellOrg/Plaster/blob/v2/Plaster/Private/Write-PlasterLog.ps1#L52-L54
> 
> Could you please fix soonish, or would you recommend we pin an old
version?</issue_description>
> 
> <agent_instructions>Search for any use of null coalescing and remove
it. This module must be able to run PS5.1</agent_instructions>
> 
> ## Comments on the Issue (you are @copilot in this section)
> 
> <comments>
> </comments>
> 


</details>



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- Fixes #442

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---

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---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: HeyItsGilbert <615265+HeyItsGilbert@users.noreply.github.com>
Co-authored-by: Gilbert Sanchez <me@gilbertsanchez.com>

Author: Copilot

CHANGELOG.md

@@ -5,7 +5,15 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
-## [2.0.0] 2025-06-18
+## [2.0.0-alpha.1] 2026-02-12
+
+### Fixed
+
+- Null-coalescing operators replaced with PS5.1-compatible syntax in
+  Write-PlasterLog to fix PowerShell 5.1 compatibility
+  ([#442](https://github.com/PowerShellOrg/Plaster/issues/442))
+
+## [2.0.0-alpha] 2025-06-18
 
 ### Added
 

Plaster/Plaster.psd1

@@ -15,7 +15,7 @@
     # PSData hashtable with additional module metadata used by PowerShell.
     PrivateData = @{
         PSData = @{
-            Prerelease = 'alpha'
+            Prerelease   = 'alpha.1'
 
             # Tags applied to this module. These help with module discovery in online galleries.
             Tags = @('Plaster', 'CodeGenerator', 'Scaffold', 'Template', 'JSON', 'PowerShell7')

Plaster/Private/Write-PlasterLog.ps1

@@ -49,9 +49,9 @@ function Write-PlasterLog {
         'Debug'       = 4
     }
 
-    $currentLogLevel = $script:LogLevel ?? 'Information'
-    $currentLevelValue = $logLevels[$currentLogLevel] ?? 2
-    $messageLevelValue = $logLevels[$Level] ?? 2
+    $currentLogLevel = if ($null -ne $script:LogLevel) { $script:LogLevel } else { 'Information' }
+    $currentLevelValue = if ($null -ne $logLevels[$currentLogLevel]) { $logLevels[$currentLogLevel] } else { 2 }
+    $messageLevelValue = if ($null -ne $logLevels[$Level]) { $logLevels[$Level] } else { 2 }
 
     if ($messageLevelValue -gt $currentLevelValue) {
         return

tests/Manifest.tests.ps1

@@ -4,8 +4,10 @@ BeforeAll {
         . $path -Task Build
     }
     # NEW: Pre-Specify RegEx Matching Patterns
-    $gitTagMatchRegEx = 'tag:\s?.(\d+(\.\d+)*)' # NOTE - was 'tag:\s*(\d+(?:\.\d+)*)' previously
-    $changelogTagMatchRegEx = "^##\s\[(?<Version>(\d+\.){1,3}\d+)\]"
+    # Matches semantic versioning with optional pre-release and build metadata
+    # Examples: 1.0.0, 2.0.0-alpha, 2.0.0-alpha.1, 2.0.0+build.123
+    $gitTagMatchRegEx = 'tag:\s?.(\d+(?:\.\d+)*)(?:-[0-9A-Za-z.-]+)?(?:\+[0-9A-Za-z.-]+)?'
+    $changelogTagMatchRegEx = "^##\s\[(?<Version>(\d+\.){2}\d+)(?:-[0-9A-Za-z.-]+)?(?:\+[0-9A-Za-z.-]+)?\]"
 
     $moduleName = $env:BHProjectName
     $manifest = Import-PowerShellDataFile -Path $env:BHPSModuleManifest