feat(tools): seed guest state at boot so captures render wallpapers (item 28c)

theme-shot guests had no ~/.nomarchy, so the session's exec-once
`nomarchy-theme-sync wallpaper` died on missing state and captures
showed a bare base-color backdrop. Seed theme-state.json via tmpfiles
before greetd starts the session — the real exec-once path now paints.
(A post-boot testScript seed is too late for exec-once, and a manual
re-run fails without WAYLAND_DISPLAY: awww's client socket is
display-named.)

V2: summer-night capture renders wallpaper + inverted cream bar +
menu + placeholder dim, all coherent.

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

agent/BACKLOG.md

@@ -99,10 +99,17 @@ review:
     0xFFEFF1F5); captures show dark because awww's empty-state layer
     paints over it in the wallpaper-less VM — on hardware the fix
     covers its intended window (the pre-awww startup gap).
-  - Harness gap: wallpaper needs `~/.nomarchy` seeded in the guest
-    (theme-sync reads runtime state there) — add before vibe-review
-    captures; latte + an identity theme (lumon/retro-82) captures
-    still pending;
+  - ✓ Harness gap fixed (iteration #44): guest `~/.nomarchy` seeded
+    via tmpfiles BEFORE greetd starts the session, so the session's
+    own exec-once wallpaper paint runs (a post-boot testScript seed
+    was too late for exec-once, and a manual re-run fails without
+    WAYLAND_DISPLAY — awww's client socket is display-named).
+    Wallpaper-complete summer-night capture reviewed: lakeside night
+    scene + cream inverted bar + menu-over-scene all cohere; the
+    placeholder dim (#2d353b99) renders. Note: summer-night's cream
+    bar/menu on dark backdrop is the authored inverted design (fg as
+    surface), not a rendering bug.
+  - An identity theme (lumon/retro-82) vibe capture still pending;
 (d) the whole-swap themes brought to the same bar (module parity
 verified textually 2026-07-05: whole-swaps carry every functional
 module; omitting cpu/memory is identity). Visual work is