feat(theme): capture Boreal picker preview + V2-verify default

Close the honesty gap on #45. Rendered the full Boreal desktop
headlessly (tools/theme-shot.nix, softGL 1920x1080) and confirmed the
session reads as Boreal — aurora wallpaper, Waybar violet accent
(#B79BE8) workspace pill, GeistMono clock, rofi launcher violet
prompt/selection — not Tokyo Night. Added themes/boreal/preview.png
(480x270, matches the existing 21) so the picker row is no longer
plain-name.

theme-shot: park the cursor bottom-right before the desktop shot so the
frame (which doubles as the preview source) is clean; reusable for the
other two missing previews.

Verified: V0 flake check; V2 theme-shot desktop/menu shots viewed;
contrast 24x7 pass. Preview is a headless bare-desktop capture (not the
floating-terminal composition of the others) — hardware recapture noted.

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

agent/JOURNAL.md

@@ -17,6 +17,25 @@ Template:
 
 ---
 
+## 2026-07-09 — #45 V2 verify Boreal default + capture preview.png (theme-shot)
+- **Task:** NEXT #45 — close the honesty gap on Boreal-as-default (shipped V0
+  only at #42) and capture the picker preview. VM-capable environment (KVM).
+- **Did:** Rendered the full Boreal desktop headlessly via `tools/theme-shot.nix`
+  (softGL, 1920×1080). Confirmed the session reads as **Boreal** — aurora
+  wallpaper paints, Waybar violet accent (`#B79BE8`) workspace pill, GeistMono
+  clock, rofi launcher violet prompt/selection — not Tokyo Night. Captured a
+  480×270 `themes/boreal/preview.png` (matches the other 21's format) from the
+  desktop frame; added a cursor-park to theme-shot so the shot is clean. (En
+  route, found+fixed the windowrule banner — separate commit `ed7fd93`.)
+- **Verified:** V0 flake check green; **V2** theme-shot desktop.png + menu.png
+  viewed (banner gone post-fix, bar+launcher themed). Scripted: contrast 24×7
+  pass; audit boreal advisory-only.
+- **Pending:** preview is a headless bare-desktop capture, not the
+  floating-terminal composition of the other 21 — hardware recapture noted
+  under theme polish. V3 (real panel/GPU) not done — not required. The float
+  rules now parse but weren't exercised on real windows (item 41 territory).
+- **Next suggestion:** #46 (install swap=0 / LUKS fail-closed) — driver ready.
+
 ## 2026-07-09 — Fix Hyprland windowrule config-error banner (windowrule 0.53 migration)
 - **Task:** bug tripped over while doing #45 (VM Boreal verify) — the default
   desktop showed a red Hyprland config-error banner on every boot, occluding