feat(bar): idle-inhibit (caffeine) toggle — generated bar + summer-day parity (item 13 slice)

Summer-night's whole-swap bar had an idle_inhibitor the generated bar
lacked (reverse parity gap from the 2026-07-04 sweep). The generated
bar now carries it — 󰾪 click → 󰅶, warm tint while active, tooltips
saying what it holds — blocking hypridle's lock/display-off/suspend
for videos and presentations; state deliberately resets with the bar.
summer-day mirrors summer-night's module + CSS, and the keybinds
cheatsheet mentions the bar click (via keybinds.extra).

V1: rendered config has the module with correct glyphs, CSS rules
present, cheatsheet row renders. Inhibit behaviour needs a session →
V3 queued.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

modules/home/keybinds.nix

@@ -76,5 +76,6 @@
     { keys = "SUPER + SHIFT + 1-9";  desc = "Move window to workspace 1-9"; }
     { keys = "SUPER + drag";         desc = "Move (LMB) / resize (RMB) window"; }
     { keys = "Volume / Brightness";  desc = "Hardware keys, shown via the OSD"; }
+    { keys = "Bar: 󰾪 click";         desc = "Caffeine — hold the screen awake (idle inhibitor)"; }
   ];
 }