#2035 Add opt-in Windows Tray for local status and diagnostics

Beschreibung

## Title

Add an opt-in read-only Windows Tray for server status and diagnostics

Related feature request: #2034.

## Summary

Windows users can check a running local Strata server, open its Web UI and copy
a short diagnostics report from the notification area. The client is built and
launched explicitly. All existing tracked engine, server, frontend and setup
files remain byte-identical to base 7695859aa13afb248bdb4d36f9b2e95707db079d.

## What changed

Adds `tools/windows-tray`: a .NET Framework 4.8 WinForms client, PowerShell build
script, contract checks, and an illustrated operation guide. No NuGet packages
or .NET SDK are required.

- Anonymous loopback `/v1/models` polling with bounded timeout/body size; supports
  the official alias and empty-list responses.
- Separate API/model status, Refresh status, Open Web UI, and Copy diagnostics.
- Diagnostics omit credentials, model names, private paths, raw errors and prompts.
- Official green layer-stack favicon embedded in both the executable and Tray;
  ICO frames range from 16 to 256 px. PerMonitorV2 and system-color status text.
- Exit leaves the independently managed server running.

This first PR does not manage server processes, change model settings, collect
API keys, install at login or automatically update. Protected APIs report
`auth required`; the browser keeps its normal authentication behavior.

### Appearance

<img src="https://raw.githubusercontent.com/medking82/Strata/codex/windows-tray-20261012/tools/windows-tray/screenshots/favicon.png" width="32" height="32" alt="Official Strata favicon">

![Local full-featured Tray — visual reference only](https://raw.githubusercontent.com/medking82/Strata/codex/windows-tray-20261012/tools/windows-tray/screenshots/local-tray-reference.png)

**Visual reference from the author's installed full-featured Tray, not this PR's
read-only client.** This original PNG replaces the low-resolution preview and
shows the shared official favicon and native menu styling. Model/context
switching, idle management, updates, logs, lifecycle/Web UI status and server
shutdown visible here belong to the separate local integration; they are not
part of this PR. The submitted menu contains API/model status, Open Web UI,
Refresh status, Copy diagnostics and Exit Tray (keep server running).

### Quick start

Start the server using the existing Strata launcher, then from repository root:

```powershell
.\tools\windows-tray\Build.ps1
.\dist\windows-tray\StrataTray.exe
# Use the port of your running server, if different:
.\dist\windows-tray\StrataTray.exe --port 8080
```

Keep `StrataTray.exe.config` next to the executable. Right-click the green icon
(in taskbar overflow if needed); double-click opens the Web UI. Copy diagnostics
then paste into an issue draft and review before sharing. Exit Tray does not stop
the server. [Full operation guide](https://github.com/medking82/Strata/blob/codex/windows-tray-20261012/tools/windows-tray/README.md).

## Extra Notes

- 45 checks passed on Windows, including 44 fixture/DPI/privacy checks and actual
  compatibility with the unmodified official mock server. Native x64 build passed.
- Copy diagnostics was clicked in the candidate menu; the clipboard reported
  API available, model loaded and HTTP 200, matching that mock server.
- No CUDA/HIP/SYCL file is touched; no GPU build or inference benchmark is claimed.
- Physical 4K/multi-monitor transitions remain manual validation. The current icon
  capture and Windows process DPI checks do not establish those results.
- Kept as a Draft PR for feedback on this narrow optional client.