feat(bar): group rhythm + semantic @muted dim states (item 28c)

Two polish items from the 1080p review. The right cluster gains a
wider breath (margin-left 14px) before each functional group — media
(pulseaudio/cpu/memory), toggles (powerprofile/nightlight/language),
status (battery/updates/notification); a self-hiding group head
degrades to the uniform spacing. Dim states (inactive workspaces, DND
bell, muted volume) move from alpha(@text, 0.5) tints to the
palette's @muted role — safe now that 28b floor-gates muted/base >=
2.0 in every theme; the CSS comment that warned against @muted
documented the pre-28b palettes and now states the new invariant.
Whole-swap bars untouched (authored identity).

Verified: V0; V1 (rendered CSS carries the rule + 4 @muted uses);
visual — tokyo-night 1080p re-capture shows the themed backdrop
(iteration #35's fix, navy not black), the group gap, and legible
muted workspaces.

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

agent/BACKLOG.md

@@ -76,12 +76,13 @@ review:
   - **Icon weight mix `[human]`:** full-color Papirus icons in the
     menus vs all-monochrome bar glyphs — pick: symbolic/monochrome
     menu icons for one system, or color as the menu's identity.
-  - **Bar right-cluster rhythm:** confirmed at 1080p — add group
-    margins (tray/net · stats · toggles · battery/notify) on the
-    gaps grid.
-  - **Semantic dim:** bar dim states are `alpha(@text, 0.5)` tints;
-    the palette's `muted` role is now floor-guaranteed (28b) — one
-    semantic source, use `@muted`.
+  - ✓ **Bar right-cluster rhythm** (shipped iteration #36): group
+    margins before pulseaudio/powerprofile/battery — heads that
+    self-hide degrade to the uniform spacing.
+  - ✓ **Semantic dim** (shipped iteration #36): workspaces + dnd +
+    muted-volume now use `@muted` (floor-guaranteed by 28b) instead
+    of `alpha(@text, 0.5)` tints; the CSS comment now documents the
+    new invariant.
   - ✓ **compositor backdrop** (shipped iteration #35): Hyprland
     `misc:background_color` now the theme's base — no more black flash
     behind a missing/slow wallpaper (glaring on light themes in the