Vendor helgoboss/helgobox (ReaLearn) as basis for custom UI fork

Stripped upstream git history; starting point for replacing the native
SWELL/Win32 mapping UI with something more suited to bulk editing.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

plugin-reaper-realearn/.github/workflows/windows-i686.yml

@@ -0,0 +1,31 @@
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+  workflow_dispatch:
+  # For quickly detecting important differences in runner configurations
+  schedule:
+    - cron: '0 5 * * MON'
+
+name: Windows i686
+
+jobs:
+  test:
+    name: Build
+    runs-on: windows-2022
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - uses: ./.github/actions/post-checkout
+        with:
+          playtime-engine-deploy-key: ${{ secrets.PRIVATE_PLAYTIME_CLIP_ENGINE_DEPLOY_KEY }}
+          license-processor-deploy-key: ${{ secrets.PRIVATE_HELGOBOSS_LICENSE_PROCESSOR_DEPLOY_KEY }}
+      - uses: ./.github/actions/build
+        with:
+          # Prevent "LLVM ERROR: out of memory"
+          args: '--features egui --profile dev-llvm-out-of-memory-fix --target i686-pc-windows-msvc'
+          targets: 'i686-pc-windows-msvc'
+          test: 'false'