fix(theme): wire obsidian sync into theme-set; drop vscode placeholder

Phase B verdict on two unused? entries in the theme-engine scripts.

- nomarchy-theme-set-obsidian: real script that copies the active
  theme's obsidian.css into every Obsidian vault under
  ~/.config/obsidian/obsidian.json. Wires it into nomarchy-theme-set
  next to the btop/opencode hot-reloads. Self-gates twice (no
  obsidian.css → exit 0; no .obsidian dir → continue), so it's a
  no-op for users without Obsidian.

- nomarchy-theme-set-vscode: delete-dead. Its own comment admitted
  it was "mostly a placeholder"; its only action (nomarchy-env-update)
  is already done unconditionally upstream by nomarchy-theme-set.
  The NOMARCHY_TOGGLE_SKIP_VSCODE_THEME env var it gated on is
  exported by features/scripts/default.nix:73 from
  nomarchy.toggles.skipVsCodeTheme, but with this script gone there
  are no consumers; the toggle survives as a public option until a
  follow-up wires it through the VSCode module properly.

SCRIPTS.md regenerated: unused? 34 → 32, kept 165 → 166. nix flake
check clean.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

themes/engine/scripts/nomarchy-theme-set

@@ -64,6 +64,10 @@ command -v nomarchy-restart-waybar >/dev/null 2>&1 && nomarchy-restart-waybar ||
 command -v nomarchy-restart-btop     >/dev/null 2>&1 && nomarchy-restart-btop     || true
 command -v nomarchy-restart-opencode >/dev/null 2>&1 && nomarchy-restart-opencode || true
 
+# Sync palette into Obsidian vaults (no-op when the user has no Obsidian
+# config or no obsidian.css template in the active theme).
+command -v nomarchy-theme-set-obsidian >/dev/null 2>&1 && nomarchy-theme-set-obsidian || true
+
 # Reload the wallpaper — its ExecStart path is stable (~/.config/nomarchy/current/background)
 # so sd-switch does not detect a unit change when only the symlink target moves.
 systemctl --user restart nomarchy-wallpaper.service 2>/dev/null || true