Improve portable package layout

[rimtty]

What changed

• add a small native QuickPods.exe launcher at the portable package root
• move the WPF application, runtime files, and helper processes into app
• collect QuickPods and .NET legal notices under licenses
• add a bilingual portable-package README with startup, security, and update guidance
• validate the portable directory layout, manifest metadata, version, and self-contained runtime files
• update CI, release packaging, installer payload generation, tests, and documentation for the new layout

Why

The previous self-contained ZIP exposed hundreds of runtime files and several executables at its root, making it difficult for users to identify the correct application entry point. The new layout leaves one obvious launcher at the root while preserving the existing sibling relationship between the internal application and helper processes.

User impact

Users extract the full ZIP and start the root QuickPods.exe. Internal files remain under app, and license files are available under licenses. Startup registration and installer cleanup continue to target or forward to the internal application as appropriate.

Validation

• dotnet restore QuickPods.sln --locked-mode
• dotnet format QuickPods.sln --verify-no-changes --no-restore
• dotnet build QuickPods.sln -c Release --no-restore (0 warnings, 0 errors)
• launcher tests: 4 passed
• Foundation tests: 136 passed
• dependency audit: 21 projects, 0 vulnerable package entries
• repository public-readiness check passed
• built and re-extracted QuickPods-0.1.2-rc.1-win-x64.zip
• portable layout, manifest, version, executable set, self-contained runtime, installer fragment, and SHA-256 verification passed
• manual launch and application behavior verified on Windows 11

One existing environment-sensitive taskbar USER-handle growth test failed locally (13 to 31 handles); this change does not touch that implementation. GitHub Actions is used as the merge gate for the complete suite.