Fix Store package runtime layout

[TheBeems]

Summary

• publish the Store MSIX with a complete self-contained .NET application layout instead of single-file metadata
• require the managed entry assembly, dependency metadata, runtime configuration, and core runtime assemblies in final package validation
• apply the same completeness checks to development integration preflight
• document the package layout and record the startup fix in the changelog

Root cause

The Store packaging target included the regular .NET apphost while single-file publish metadata excluded CodexUsageDock.dll and CodexUsageDock.runtimeconfig.json. The resulting MSIX passed the previous runtime-file checks but failed before managed code started because the apphost could not find its managed entry assembly.

Impact

Store packages now remain a single MSIX installation unit for users while carrying an explicit, verifiable app-local .NET layout internally. Incomplete packages matching the Partner Center crash signature are rejected during the release build.

Validation

• x64: 77 tests passed; Debug build passed
• ARM64: 77 tests passed; Debug build passed
• full x64 + ARM64 Store release build passed
• final 0.5.1.msixupload inspected: both packages contain the managed entry assembly, deps file, runtimeconfig, System.Private.CoreLib, and native host/runtime files
• PowerShell syntax and git diff --check passed
• integration manifest, runtime, asset, CLSID, COM, and AppExtension preflight checks passed

Local development registration could not be refreshed because Windows reported a conflicting unpackaged installation under another user (0x80073D19). Manual Command Palette reload verification therefore remains outstanding.