feat(displays): declarative nomarchy.monitors + nwg-displays arranger

Add a per-output monitor schema (name / resolution / position / scale /
transform / mirror / bitdepth / vrr / disable) that generates Hyprland
`monitor` rules, keeping the ,preferred,auto,1 wildcard as the fallback.
Hyprland applies the rules on hotplug, so a declared external/dock output
arranges itself on connect (no kanshi -- it fights Hyprland's own output
management). Default [] -> wildcard only, so no change for existing setups;
set wayland.windowManager.hyprland.settings.monitor directly to override.

nwg-displays ships behind nomarchy.displays.enable (default true) as an
interactive arranger -- a helper to discover values; the declarative config
stays the source of truth (its output file isn't sourced).

Remaining (roadmap): docked/undocked profile switching, workspace-to-monitor
binding.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

README.md

@@ -201,6 +201,8 @@ examples: **[docs/OVERRIDES.md](docs/OVERRIDES.md)**.
 | `nomarchy.stylix.enable` | `true` | GTK/Qt/cursor theming |
 | `nomarchy.fastfetch.enable` | `true` | fastfetch fronted by the themed Nomarchy logo |
 | `nomarchy.keys.enable` | `true` | gpg-agent fronting SSH + pinentry-qt |
+| `nomarchy.displays.enable` | `true` | nwg-displays interactive monitor arranger (helper for `nomarchy.monitors`) |
+| `nomarchy.monitors` | `[]` | Declarative per-output layout → Hyprland `monitor` rules (applied on hotplug); `,preferred,auto,1` wildcard kept as fallback |
 | `nomarchy.themesDir` | Nomarchy's `themes/` | Where per-theme app overrides are probed |
 | `nomarchy.system.plymouth.enable` | `true` | Branded boot splash, background from the theme JSON (recolors on system rebuilds) |
 | `nomarchy.system.fileManager.enable` | `true` | Thunar GUI + gvfs/tumbler/udisks2 (the "open folder" handler) |