Lock theme to dark only and brighten footer UI

- Remove light palette and toggle from mkdocs.yml (theme button disappears, dark forced)
- Brighten footer top border, footer-meta border, copyright, and social icons for better contrast against dark background

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: ORB-8888

docs/stylesheets/extra.css

@@ -743,7 +743,7 @@ body {
 .md-footer {
   background-color: var(--one-bg-elev);
   color: var(--one-fg);
-  border-top: 1px solid var(--one-border);
+  border-top: 1px solid var(--one-border-strong);
 }
 
 .md-footer__inner {
@@ -752,7 +752,14 @@ body {
 
 .md-footer-meta {
   background-color: var(--one-bg-elev-2);
-  color: var(--one-fg-muted);
+  color: var(--one-fg);
+  border-top: 1px solid var(--one-border-strong);
+}
+
+.md-footer-meta .md-footer-copyright,
+.md-footer-meta .md-footer-copyright__highlight {
+  color: var(--one-fg);
+  opacity: 1;
 }
 
 .md-footer__link {
@@ -778,6 +785,30 @@ body {
   letter-spacing: 0.1em;
 }
 
+.md-social {
+  padding: 0.4rem 0;
+}
+
+.md-social__link {
+  color: var(--one-fg);
+  opacity: 1;
+  transition: color 0.15s ease, transform 0.15s ease;
+}
+
+.md-social__link svg {
+  fill: var(--one-fg);
+}
+
+.md-social__link:hover,
+.md-social__link:focus {
+  color: var(--one-accent);
+  transform: translateY(-1px);
+}
+
+.md-social__link:hover svg {
+  fill: var(--one-accent);
+}
+
 /* ============================================================
    15. SEARCH
    ============================================================ */

mkdocs.yml

@@ -16,18 +16,9 @@ theme:
   logo: assets/images/logo.png
   favicon: assets/images/logo.png
   palette:
-    - scheme: default
-      primary: custom
-      accent: custom
-      toggle:
-        icon: material/brightness-7
-        name: Switch to dark mode
     - scheme: slate
       primary: custom
       accent: custom
-      toggle:
-        icon: material/brightness-4
-        name: Switch to light mode
   features:
     - navigation.instant
     - navigation.instant.progress