Twelve themes, and the Theme section folds away

Seven more palettes: Midnight (indigo, violet), Moss (forest floor, lime),
Plum (aubergine, purple), Sepia (warm brown with a cool teal — Ember's
arrangement reversed), Blackout (true black for a dark room, where any glow
off the screen carries), Paper (the warm light one, next to Daylight's cool
white) and Iron, which has no colour of its own: its accent is near-white, so
the only hues on screen are a module's own and the red and amber that mean
something.

Each holds the line the first five set. Text on panel lands between 14.8:1
and 19.8:1, muted between 5.8:1 and 7.4:1, and every accent clears its own
theme's danger red and warning amber by more than Ember already does — the
narrowest of the new ones is Moss at 54 degrees of hue, against Ember's 18.

The Theme section now starts folded, wearing the same disclosure triangle as
a module's config groups. A building picks its palette once and then wants
the rest of the page, which was getting further down the screen with every
swatch.

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

public/admin/index.html

@@ -41,9 +41,11 @@
     </section>
 
     <section id="theme-section" hidden>
-      <h1 class="admin-h1">Theme</h1>
-      <div class="theme-swatches" id="theme-swatches" role="radiogroup" aria-label="Theme"></div>
-      <div class="admin-status" id="theme-status"></div>
+      <details class="admin-fold">
+        <summary class="admin-h1 admin-fold-title">Theme</summary>
+        <div class="theme-swatches" id="theme-swatches" role="radiogroup" aria-label="Theme"></div>
+        <div class="admin-status" id="theme-status"></div>
+      </details>
     </section>
 
     <section id="modules-section" hidden>