Remove legacy WPF app, flatten WinUI project to repo root, rename namespace

The repo carried two parallel UIs (WPF + WinUI) sharing Models/Services via
cross-directory Link includes. Now that WinUI is the only frontend, collapse
the structure so the WinUI project IS the repo root instead of a nested
sibling folder:

- Delete the WPF project entirely (App.xaml, MainWindow.xaml, csproj) and its
  bin/obj output
- Move AmiReel.WinUI/* up to the repo root (App, MainWindow, MainPage,
  DialogHelper, Assets, Package.appxmanifest, app.manifest, Properties,
  .github/instructions, AGENTS.md) via git mv, preserving history
- Rename AmiReel.WinUI.csproj -> AmiReel.csproj; regenerate the solution as
  AmiReel.slnx (the newer XML solution format) with a single project
- Rename namespace AmigaDB.VideoRenderer.{Models,Services} -> AmiReel.{...}
  and AmiReel_WinUI -> AmiReel across all files, including the embedded
  ffmpeg/ffprobe resource logical names in the csproj and ToolExtractor
- Models/ and Services/ no longer need the Link-based cross-directory
  <Compile Include>; they're picked up by the SDK's default globbing now
  that they live under the project directory
- Rename assets/ -> branding/ (source icon art) to avoid a case-insensitive
  collision with Assets/ (packaged tile art) once both sit at repo root
- Merge the two .gitignore files into one; track the PublishProfiles pubxml
  files instead of ignoring them (no secrets, and they keep publish
  reproducible across machines) as branding, gitignore, etc.
- Simplify publish-win-x64.ps1 (drop the -Target Wpf/WinUI switch, there's
  only one target now) and rewrite README.md to describe the single-project
  layout, build/run/publish commands, and file structure

Verified: dotnet build succeeds for both AmiReel.csproj and AmiReel.slnx, and
the built exe launches and renders identically to before the move.

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

.github/instructions/globalization.instructions.md

@@ -0,0 +1,55 @@
+---
+description: 'Globalization & Localization requirements for user-facing strings, resource files, and culture-aware formatting'
+applyTo: '**/*.cs, **/*.xaml, **/*.resw'
+---
+
+# Globalization & Localization
+
+These rules apply to **every feature and change** involving user-facing text. They are not optional add-ons.
+
+---
+
+## Rules
+
+- **All user-facing strings** (UI text, error messages, tooltips) must come from `.resw` resource files — never hard-code them in XAML or C#.
+- Resource file location: `Strings/en-us/Resources.resw` (default locale).
+- Use `x:Uid` in XAML to bind controls to resource keys:
+  ```xml
+  <TextBlock x:Uid="WelcomeMessage" />
+  ```
+  With a matching `.resw` entry: `WelcomeMessage.Text` = "Welcome!"
+- In code-behind / ViewModels, use the `ResourceLoader`:
+  ```csharp
+  var loader = new Microsoft.Windows.ApplicationModel.Resources.ResourceLoader();
+  string message = loader.GetString("ErrorFileNotFound");
+  ```
+- **Format dates, numbers, and currencies** using `CultureInfo.CurrentCulture` or `DateTimeFormatter` — never assume a specific regional format.
+- Avoid concatenating translated strings — use format placeholders (`{0}`, `{1}`).
+- Design UI layouts to accommodate text expansion (~30-40% longer for German vs. English).
+
+## Anti-patterns
+
+- Hard-coded strings in `.xaml` or `.cs` files (e.g., `Content="Save"`).
+- Using `string.Format` with hard-coded ordinal assumptions.
+- Fixed-width UI elements that clip translated text.
+
+## Validation
+
+- Build & register the MSIX package — see **Build, Run & Deploy** in `.github/agents/Agents.md`.
+- Check for hard-coded strings: search `Content="` and `Text="` in `.xaml` files — replace with `x:Uid`.
+
+### Verification Checklist
+
+- [ ] All user-facing strings are in `.resw` resource files
+
+## Must Read & Research
+
+> **Agent Rule:** Before any localization-related change, you **must** fetch and review these references using `fetch_webpage`. Apply what you learn.
+
+| # | Reference | When to consult |
+|---|---|---|
+| 1 | [Globalize your WinUI app](https://learn.microsoft.com/en-us/windows/apps/design/globalizing/guidelines-and-checklist-for-globalizing-your-app) | Adding any new user-facing strings or culture-aware formatting |
+| 2 | [Resource Management System](https://learn.microsoft.com/en-us/windows/apps/windows-app-sdk/mrtcore/localize-strings) | Setting up or modifying `.resw` files and `ResourceLoader` usage |
+| 3 | [WinUI Localization with x:Uid](https://learn.microsoft.com/en-us/windows/apps/develop/ui-input/localizing-strings) | Binding XAML controls to localized resources via `x:Uid` |
+
+