feat(themes): wallpapers split — 94 MB of runtime-only images leave the flake source

The split line is consumption time: palette JSONs, previews and
per-theme overrides are read at Nix eval and stay in-repo (~3 MB);
wallpapers are runtime-only (swww via nomarchy-state-sync, never read
at eval) and move to the pinned nomarchy-wallpapers non-flake input
(git.bemagri.xyz/bernardo/Nomarchy-Wallpapers @ 803b48d, all 24 slugs).

New overlay drv nomarchy-default-themes merges the two: repo themes
copied, <slug>/backgrounds symlinked from the input, build FAILS if any
theme JSON lacks non-empty backgrounds — the drift guard for the
two-repo dance. nomarchy-state-sync's wrapper now points straight at
the merged store path (no in-package copy): the package drops from
~94 MB to 32.6 KiB and the wallpapers source appears exactly once in
any system closure, ISO included — offline promise intact. Downstream
custom wallpapers still win ($NOMARCHY_PATH/themes is checked first),
and an explicit state.json wallpaper path still works.

checks re-pointed at the merged tree (theme-wholeswap,
state-sync-validate, auto-theme); theme-contrast and airplane stay on
./themes (JSON/text only). import-palettes.py + README updated;
ROADMAP § Faster switches marked shipped; LATER now carries only the
pre-built-variants follow-on. Also files #151 (v1 launch plan, [human])
with measured history numbers: the 107 MiB pack is 94 MB wallpaper
blobs; all 848 text commits pack to ~15-20 MiB — recommendation
recorded to filter-repo at the GitHub move, not fresh-start.

Verification: V2 — nix flake check --no-build green; theme-wholeswap,
state-sync-validate, auto-theme VM check, downstream-template-home all
green; wallpapers store path exactly once in the state-sync closure;
`list` works from a scratch state dir. V3 queued: live wallpaper render
+ bg-next + custom-override precedence after next pull (HARDWARE-QUEUE).
Lock gained exactly the one input node. Implementation by a Sonnet
subagent; design and review on Fable.

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

agent/JOURNAL.md

@@ -19,6 +19,26 @@ Template:
 
 ---
 
+## 2026-07-17 — Wallpapers split shipped: 94 MB out of the flake source
+- **Task:** LATER "Wallpapers artifact split" (promoted by Bernardo live —
+  he created the Nomarchy-Wallpapers repo mid-session). Also filed #151
+  (v1 launch plan, [human]) with measured history numbers.
+- **Did:** all 24 themes' backgrounds → Nomarchy-Wallpapers (803b48d,
+  pushed); new `nomarchy-wallpapers` non-flake input; overlay drv
+  `nomarchy-default-themes` merges repo themes (~3 MB) + input backgrounds
+  with a build-failing drift guard; state-sync wrapper points at the
+  merged store path (package 94 MB → 32.6 KiB); checks re-pointed;
+  `themes/*/backgrounds/` git-rm'd. Split line: eval-time assets stay
+  in-repo, runtime-only wallpapers move. Sonnet implemented; design +
+  review here.
+- **Verified:** V2 — flake check green; theme-wholeswap, state-sync-validate,
+  auto-theme VM check, template HM build all green; wallpapers source
+  exactly once in the closure; `list` works from a scratch state dir.
+- **Pending:** V3 queued (wallpaper renders + bg-next after next pull;
+  custom-wallpaper override precedence). History rewrite decision folded
+  into #151.
+- **Next suggestion:** #151 planning session with Bernardo.
+
 ## 2026-07-17 — v1-prep hygiene sweep: repo is clean; LICENSE was the real gap
 - **Task:** Bernardo asked for a structure/necessity audit + full docs sweep
   ahead of v1. Three Sonnet passes (structure, docs-vs-code, mechanical