feat(debug): DEBUG-only Debug Window with Icon Catalog
Adds a separate window dedicated to in-app debug surfaces, reachable
from a `Debug` menu that only ships in DEBUG builds. First surface is
an Icon Catalog that lists every `CommandIconMap` entry (token, icon
asset / SF Symbol fallback) rendered through the same `TabIconImage`
the tab UI uses, so the auto-detected set can be eyeballed in one
place when adding new branded artwork.
- `DebugWindowManager` mirrors `SettingsWindowManager`: cached
NSWindow + NSHostingController, configured once during app
bootstrap with the root store so the window can mirror the user's
appearance setting via `WindowAppearanceSetter` (standalone
NSWindows don't pick up `.preferredColorScheme`).
- `DebugView` is a NavigationSplitView so future debug surfaces can
be added by extending `DebugSection` and the sidebar list / detail
switch.
- `CommandIconMap.debugAllEntries` exposes the first-token mapping
for the catalog (DEBUG only).
- The Debug menu in `supacodeApp.commands` is wrapped behind
`#if DEBUG`; the existing commands are grouped under `Group { ... }`
to stay under SwiftUI's CommandsBuilder tuple-arity limit once the
Debug menu is added.
Also swaps the Codex asset for a tighter mark sourced from LobeHub
(viewBox 1 1 18 18 to match the visual weight of the other 24x24
brand SVGs).