Add OBS plugin install script

scripts/install-obs-mimir-plugin.ps1

@@ -0,0 +1,49 @@
+param(
+    [string]$ObsRoot = "",
+    [string]$Configuration = "Release",
+    [switch]$SkipBuild,
+    [switch]$WhatIf
+)
+
+$ErrorActionPreference = "Stop"
+
+$repoRoot = Split-Path -Parent $PSScriptRoot
+
+if ([string]::IsNullOrWhiteSpace($ObsRoot)) {
+    if ($env:OBS_STUDIO_ROOT) {
+        $ObsRoot = $env:OBS_STUDIO_ROOT
+    } elseif (Test-Path "C:\Program Files\obs-studio") {
+        $ObsRoot = "C:\Program Files\obs-studio"
+    } else {
+        throw "OBS root was not found. Pass -ObsRoot or set OBS_STUDIO_ROOT."
+    }
+}
+
+$pluginDll = Join-Path $repoRoot "native\obs_stem_source\build\$Configuration\mimir_obs_stem_source.dll"
+$targetDir = Join-Path $ObsRoot "obs-plugins\64bit"
+$targetDll = Join-Path $targetDir "mimir_obs_stem_source.dll"
+
+if (-not $SkipBuild) {
+    & (Join-Path $repoRoot "scripts\build-obs-stem-plugin.ps1") -Configuration $Configuration
+}
+
+if (-not (Test-Path $pluginDll)) {
+    throw "Built plugin DLL was not found at '$pluginDll'."
+}
+
+if (-not (Test-Path $targetDir)) {
+    if ($WhatIf) {
+        Write-Host "Would create $targetDir"
+    } else {
+        New-Item -ItemType Directory -Force $targetDir | Out-Null
+    }
+}
+
+if ($WhatIf) {
+    Write-Host "Would copy $pluginDll -> $targetDll"
+    return
+}
+
+Copy-Item -LiteralPath $pluginDll -Destination $targetDll -Force
+Write-Host "Installed Mimir OBS plugin: $targetDll"
+Write-Host "OBS source types: Mimir Program Texture, Mimir Audio Stem"