feat: some basic action core logic

eng/Containerfile

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+FROM mcr.microsoft.com/dotnet/sdk:10.0
+WORKDIR /work
+COPY ./src /work

src/Geekeey.Build.Pwsh.psd1

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+@{
+	RootModule        = 'Geekeey.Build.Pwsh.psm1'
+	ModuleVersion     = '1.0.0'
+	GUID              = '234baa68-d26f-4bf9-996d-45ec3520cb95'
+	Author            = 'The Geekeey Authors'
+	CompanyName       = 'Geekeey'
+	Copyright         = '(c) The Geekeey Authors. Licensed under EUPL-1.2.'
+	Description       = 'Forgejo Actions helper functions for PowerShell.'
+	FunctionsToExport = @(
+		'Set-ActionOutput',
+		'Set-ActionEnv',
+		'Add-ActionPath',
+		'Add-ActionMask',
+		'Add-ActionMatcher',
+		'Remove-ActionMatcher',
+		'Save-ActionState',
+		'Add-ActionStepSummary',
+		'Get-ActionInput',
+		'Write-ActionDebug',
+		'Write-ActionNotice',
+		'Write-ActionWarning',
+		'Write-ActionError',
+		'Stop-Action',
+		'Invoke-ForgejoApi',
+		'Get-ForgejoContext'
+	)
+	CmdletsToExport   = @()
+	VariablesToExport = @()
+	AliasesToExport   = @()
+	PowerShellVersion = '7.0'
+	PrivateData       = @{
+		PSData = @{
+			LicenseUri = 'https://joinup.ec.europa.eu/collection/eupl/eupl-text-eupl-12'
+			Tags       = @('Forgejo', 'Actions', 'CI')
+		}
+	}
+}

src/collection/checkout.ps1

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+using module ../Geekeey.Build.Pwsh.psd1

src/collection/pwsh.ps1

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+# Copyright (c) The Geekeey Authors
+# SPDX-License-Identifier: EUPL-1.2
+using module ../Geekeey.Build.Pwsh.psd1
+
+Set-StrictMode -Version Latest
+
+$ErrorActionPreference = 'Stop'
+$ProgressPreference = 'Ignore'
+
+$PSNativeCommandUseErrorActionPreference = $true
+
+$script = Get-ActionInput -Name "script" -Required
+
+try
+{
+    Invoke-Expression $script
+}
+catch
+{
+    Write-ActionError "Script failed: $_"
+    exit 1
+}

src/collection/ssh-add-key.ps1

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+using module ../Geekeey.Build.Pwsh.psm1