feat(waybar): combined power menu on the battery + profile icons

Item 36(b). Adds `nomarchy-menu powermgmt` — one flat rofi menu of power
Profile rows (→ powerprofilesctl set) + Charge limit rows (→ the same
theme-sync writer batterylimit uses), each half self-gating on its
hardware. No backend duplication; Custom charge stays in the dedicated
batterylimit picker.

Opened two ways (Bernardo's call): the Waybar battery icon AND the
power-profile icon — the profile icon's click flips from cycle → menu.
Wired in waybar.nix and all four whole-swaps (parity). Named `powermgmt`
to avoid the whole-swaps' existing `custom/powermenu` shutdown button
(→ nomarchy-menu power), which is left untouched. The granular System ▸
Power profile / Battery limit rows stay ("keep both").
nomarchy-powerprofile-cycle kept as a standalone bin, now unbound by
default.

Verified: V0 green; V1 HM built (bash -n) — powermgmt case ships, the
generated waybar-config.json wires both icons (2 hits), all four jsoncs
re-wired and still parse, shutdown buttons intact. Click→menu→apply is
V3 (queued).

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

themes/summer-day/waybar.jsonc

@@ -64,7 +64,7 @@
     "format-plugged": "<span size='13pt'></span> {capacity}%",
     "format-full": " 100%",
     "format-icons": ["", "", "", "", ""],
-    "on-click": "nomarchy-menu power",
+    "on-click": "nomarchy-menu powermgmt",
     "tooltip-format": "Battery status"
   },
 
@@ -85,7 +85,7 @@
     "return-type": "json",
     "interval": 5,
     "exec": "nomarchy-powerprofile-status",
-    "on-click": "nomarchy-powerprofile-cycle"
+    "on-click": "nomarchy-menu powermgmt"
   },
 
   "custom/recording": {