feat(display): menu-driven per-output resolution, in-flake

Phase 3 of the in-flake-state philosophy (mirroring night-light + the
keyboard-layout watcher): a System ▸ Display menu item picks an output's
resolution and persists it into the flake instead of a runtime-only tweak.

- rofi.nix: the `display` case reads `hyprctl monitors -j` (auto-skips the
  chooser with one output), lists the output's advertised modes (rounded
  refresh, deduped, highest-first) plus the preferred/highres/highrr
  tokens, applies the pick INSTANTLY via `hyprctl keyword monitor` —
  keeping the output's current position + scale, so only the resolution
  changes — then persists it with `nomarchy-theme-sync set
  settings.monitors.<name> <mode> --no-switch` (no rebuild).
- theme.nix: seed `settings.monitors = {}` (output-name -> "WxH@R") so a
  sparse/older state file still evaluates; exposed via nomarchy.settings.
- hyprland.nix: `resolvedMonitors` overlays settings.monitors onto
  nomarchy.monitors by name — a declared output keeps its other fields
  with only the resolution swapped, an undeclared output (wildcard-only,
  e.g. the laptop panel) becomes a fresh rule. So a later rebuild bakes
  the menu pick into the generated monitor rule — the monitor twin of the
  keyboard graduation. The menu pick wins over a hand-set resolution (it's
  the explicit live action).

Monitor connector names are dot-free, so a direct dotted set-path is safe
(no whole-map read-modify-write like the keyboard watcher needs).

VM-verified via a headless-Hyprland nixosTest (run + removed; too heavy
for a CI gate): the graduation baked the rule into the generated
hyprland.conf, the set/get round-trip persisted, and `hyprctl keyword
monitor` actually changed the reported resolution. Only the interactive
rofi picker isn't headlessly driveable (same caveat as the keyboard watcher).

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

modules/home/rofi.nix

@@ -280,6 +280,56 @@ ${themeRows}
           *Input*)  exec rofi-pulse-select source ;;
         esac ;;
 
+      display)
+        # Per-output resolution picker. Applies the chosen mode INSTANTLY via
+        # `hyprctl keyword monitor` — keeping the output's current position and
+        # scale, so only the resolution changes — and PERSISTS it to the in-flake
+        # state (settings.monitors.<name>, --no-switch = no rebuild), so the
+        # choice survives logout/reboot. A later rebuild bakes the same
+        # resolution into the generated monitor rule (hyprland.nix overlays
+        # settings.monitors onto nomarchy.monitors by name). Self-gated to the
+        # Hyprland session; guard here too in case it's invoked directly.
+        command -v hyprctl >/dev/null 2>&1 \
+          || { notify-send "Display" "Hyprland is not running."; exit 0; }
+        mons=$(hyprctl monitors -j)
+
+        # Choose the output (skip the chooser when only one is connected).
+        if [ "$(printf '%s' "$mons" | jq -r '.[].name' | grep -c .)" -gt 1 ]; then
+          name=$( {
+            printf '%s' "$mons" | jq -r '.[] | "\(.name)  ·  \(.width)x\(.height)@\(.refreshRate|round)Hz"'
+            printf '%s\n' "$BACK"
+          } | rofi -dmenu -p Display ) || exit 0
+          [ "$name" = "$BACK" ] && exec "$0" system
+          name=''${name%%  ·*}                       # strip the "  ·  WxH@R" hint
+        else
+          name=$(printf '%s' "$mons" | jq -r '.[0].name')
+        fi
+        [ -n "$name" ] || exit 0
+
+        # Pick a mode: a few Hyprland resolution tokens, then the output's
+        # advertised modes (rounded refresh rate, deduped, highest first). The
+        # prompt shows the current mode.
+        cur=$(printf '%s' "$mons" | jq -r --arg n "$name" \
+          '.[]|select(.name==$n)|"\(.width)x\(.height)@\(.refreshRate|round)"')
+        mode=$( {
+          printf 'preferred\nhighres\nhighrr\n'
+          printf '%s' "$mons" | jq -r --arg n "$name" '.[]|select(.name==$n)|.availableModes[]' \
+            | sed 's/Hz$//' | awk -F@ '{ printf "%s@%d\n", $1, $2 + 0.5 }' | sort -rV -u
+          printf '%s\n' "$BACK"
+        } | rofi -dmenu -p "$name (now $cur)" ) || exit 0
+        [ "$mode" = "$BACK" ] && exec "$0" display
+        [ -n "$mode" ] || exit 0
+
+        # Apply live (keep the output's current position + scale), then persist.
+        pos=$(printf '%s' "$mons" | jq -r --arg n "$name" '.[]|select(.name==$n)|"\(.x)x\(.y)"')
+        scale=$(printf '%s' "$mons" | jq -r --arg n "$name" '.[]|select(.name==$n)|.scale')
+        if hyprctl keyword monitor "$name,$mode,$pos,$scale" >/dev/null 2>&1; then
+          nomarchy-theme-sync --quiet set "settings.monitors.$name" "$mode" --no-switch
+          notify-send "Display" "$name → $mode"
+        else
+          notify-send "Display" "Could not set $name to $mode."
+        fi ;;
+
       capture)
         choice=$( {
           row "Region → clipboard"      applets-screenshooter
@@ -382,6 +432,7 @@ ${themeRows}
           row "Bluetooth"      bluetooth
           [ -e "''${XDG_RUNTIME_DIR:-/run/user/$(id -u)}/pulse/native" ] \
             && row "Audio" audio-volume-high
+          row "Display" video-display
           command -v system-config-printer >/dev/null 2>&1 && row "Printers" printer
           row "Do Not Disturb" notification-disabled
           if systemctl --user is-active --quiet hyprsunset.service 2>/dev/null
@@ -404,6 +455,7 @@ ${themeRows}
           *VPN*)              exec "$0" vpn ;;
           *Bluetooth*)        exec "$0" bluetooth ;;
           *Audio*)            exec "$0" audio ;;
+          *Display*)          exec "$0" display ;;
           *Printers*)         exec "$0" printers ;;
           *"Do Not Disturb"*) exec "$0" dnd ;;
           *"Night light"*)    exec "$0" nightlight ;;
@@ -434,7 +486,7 @@ ${themeRows}
         esac ;;
 
       *)
-        echo "usage: nomarchy-menu [tools|system|power|power-profile|theme|clipboard|calc|files|emoji|web|network|bluetooth|audio|printers|capture|keybinds|ask|dnd|nightlight|autotimezone|vpn|snapshot]" >&2
+        echo "usage: nomarchy-menu [tools|system|power|power-profile|theme|clipboard|calc|files|emoji|web|network|bluetooth|audio|display|printers|capture|keybinds|ask|dnd|nightlight|autotimezone|vpn|snapshot]" >&2
         exit 64 ;;
     esac
   '';