site: reconcile color tokens to canonical desktop palette

Per DESIGN-SYSTEM.md, the desktop CSS values are canonical and the
site has been drifting on 11 of 13 color tokens. This brings the site
:root block in line. Token-only change in the dark-mode block.

What this does:
  --bg:           #1a1410 → #191410
  --bg2:          #241e18 → #1e1812
  --bg3:          #2e261e → #241d15
  --rust:         #c45d2c → #e8763a
  --rust-light:   #e8753a → #f0a16e
  --leather:      #a0845c → #c6a778
  --leather-light: #c4a87a → #d9c198
  --cream:        #f0e6d3 → #f5e9d3
  --cream-dim:    #bfb5a3 → #c9b896
  --cream-muted:  #7a7060 → #8a7a60
  --gold:         #d4a843 → #d4a84b

What this doesn't touch:
  - The light-mode @media block (line 35). Per the design system,
    light mode is a fallback for accessibility, not a designed mode.
    Iterating on it is explicitly out of scope.
  - The 22 hardcoded hex values in inline SVGs (brand mark + the
    dashboard mockup further down the page). These reference the OLD
    palette values. They're now slightly drifted from :root, which is
    a design-system violation.

    Followup TODO: the SVG mockups need a separate eyes-on pass to
    decide which hex values to update — the dashboard SVG isn't just
    color, it's a careful rendering of relative contrast that may not
    survive a naive find-and-replace. Doing that pass at midnight
    three days from launch is exactly the wrong move. Tracking as
    pre-launch followup.

Verification:
  - make site-sync clean
  - go build ./internal/site/... clean
  - Diff is 11 hex values per file, 22 lines total
  - Secret scan: 0 hits

Author: claude

internal/site/static/index.html

@@ -23,11 +23,11 @@
 <style>
 *{margin:0;padding:0;box-sizing:border-box}
 :root{
-  --bg:#1a1410;--bg2:#241e18;--bg3:#2e261e;
-  --rust:#c45d2c;--rust-light:#e8753a;
-  --leather:#a0845c;--leather-light:#c4a87a;
-  --cream:#f0e6d3;--cream-dim:#bfb5a3;--cream-muted:#7a7060;
-  --gold:#d4a843;--green:#4a9e5c;--green-light:#6bb87f;
+  --bg:#191410;--bg2:#1e1812;--bg3:#241d15;
+  --rust:#e8763a;--rust-light:#f0a16e;
+  --leather:#c6a778;--leather-light:#d9c198;
+  --cream:#f5e9d3;--cream-dim:#c9b896;--cream-muted:#8a7a60;
+  --gold:#d4a84b;--green:#4a9e5c;--green-light:#6bb87f;
   --font-serif:'Libre Baskerville',Georgia,serif;
   --font-mono:'JetBrains Mono',monospace;
 }

site/index.html

@@ -23,11 +23,11 @@
 <style>
 *{margin:0;padding:0;box-sizing:border-box}
 :root{
-  --bg:#1a1410;--bg2:#241e18;--bg3:#2e261e;
-  --rust:#c45d2c;--rust-light:#e8753a;
-  --leather:#a0845c;--leather-light:#c4a87a;
-  --cream:#f0e6d3;--cream-dim:#bfb5a3;--cream-muted:#7a7060;
-  --gold:#d4a843;--green:#4a9e5c;--green-light:#6bb87f;
+  --bg:#191410;--bg2:#1e1812;--bg3:#241d15;
+  --rust:#e8763a;--rust-light:#f0a16e;
+  --leather:#c6a778;--leather-light:#d9c198;
+  --cream:#f5e9d3;--cream-dim:#c9b896;--cream-muted:#8a7a60;
+  --gold:#d4a84b;--green:#4a9e5c;--green-light:#6bb87f;
   --font-serif:'Libre Baskerville',Georgia,serif;
   --font-mono:'JetBrains Mono',monospace;
 }