Enable DevTools MCP and improve system monitor layout and refresh

[Marc-André Moreau (mamoreau-devolutions)]

Summary

• Add opt-in AvaloniaUI.DiagnosticsSupport 2.2.3 to the NativeAOT host via -DeveloperTools, with separate development bundles and no diagnostics in normal builds.
• Compact and rebalance summary cards, provide scrollable CPU details, align toolbar buttons, and use 36px process rows.
• Resolve account names when available and add tooltips for truncated process/user names.
• Replace windowed process-page invalidation with persistent PID/start-time-keyed row models and incremental collection updates to avoid refresh placeholder churn.
• Regenerate view-model bindings and document usage and limitations.

Validation

• Built normal and diagnostics-enabled NativeAOT bundles; rebuilt diagnostics bundle after layout/refresh changes.
• Packaging helper/scaffold regressions passed; all 20 system-monitor Rust tests passed.
• Attached Avalonia DevTools MCP to the actual Rust executable and exercised tree/property inspection, screenshots, search filtering, CPU scrolling, and selection across refreshes.
• Inspected layouts at 1400x900 and 1100x700.

Notes

• Runtime XAML loading/hot reload remains unsupported in NativeAOT. DiagnosticsSupport emits an upstream bitmap ABI warning, although the exercised MCP screenshot path works.
• Process models now remain resident for all filtered processes; visual rows remain virtualized.
• Instrumented bundles are development-only and must not be distributed.
• The producer submodule revision is unchanged; local application of the existing producer patch is not part of this PR.