Mobile-responsive admin nav/thread header, real dark theme pass

Nav overflowed the viewport on phones (confirmed via screenshot) — header
now wraps, nav row scrolls horizontally instead of pushing user/theme/
logout off-screen, ticket-thread's status/assignee selects stack full-width
below the subject on narrow screens.

Dark theme got a real pass instead of reusing near-identical values:
deeper/richer surfaces, punchier accent (#8b5cf6, matches the already-
validated dark chart-1), a subtle violet glow behind the page, and a
dark-appropriate card shadow (inset highlight + soft shadow — the flat
black shadow from light mode was invisible on a dark surface).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QcXH24ky6zjk2UyK5oZUPH

src/app/globals.css

@@ -99,23 +99,26 @@
   --radius-md-val: 12px;
   --radius-lg-val: 18px;
 
+  --bg-glow: none;
+  --card-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
+
   color-scheme: light;
 }
 
 @media (prefers-color-scheme: dark) {
   :root:not([data-theme="light"]) {
-    --bg: #0f0d17;
-    --surface: #17141f;
-    --surface-hover: #1e1a2b;
-    --border: #2b2438;
-    --border-strong: #3a3150;
+    --bg: #0b0a12;
+    --surface: #161320;
+    --surface-hover: #1d1929;
+    --border: #2d2640;
+    --border-strong: #453c60;
     --text: #f1eefb;
     --text-muted: #a79fc4;
     --text-faint: #6f6790;
 
-    --accent: #a78bfa;
-    --accent-hover: #c4b5fd;
-    --accent-soft: #241b3d;
+    --accent: #8b5cf6;
+    --accent-hover: #7c3aed;
+    --accent-soft: #251c3f;
     --accent-soft-text: #c4b5fd;
 
     --danger: #f87171;
@@ -146,23 +149,26 @@
     --chart-4: #d97706;
     --chart-muted: var(--border-strong);
 
+    --bg-glow: radial-gradient(ellipse 80% 50% at 50% -10%, rgba(139, 92, 246, 0.12), transparent 60%);
+    --card-shadow: 0 1px 0 rgba(255, 255, 255, 0.05) inset, 0 8px 24px rgba(0, 0, 0, 0.35);
+
     color-scheme: dark;
   }
 }
 
 :root[data-theme="dark"] {
-  --bg: #0f0d17;
-  --surface: #17141f;
-  --surface-hover: #1e1a2b;
-  --border: #2b2438;
-  --border-strong: #3a3150;
+  --bg: #0b0a12;
+  --surface: #161320;
+  --surface-hover: #1d1929;
+  --border: #2d2640;
+  --border-strong: #453c60;
   --text: #f1eefb;
   --text-muted: #a79fc4;
   --text-faint: #6f6790;
 
-  --accent: #a78bfa;
-  --accent-hover: #c4b5fd;
-  --accent-soft: #241b3d;
+  --accent: #8b5cf6;
+  --accent-hover: #7c3aed;
+  --accent-soft: #251c3f;
   --accent-soft-text: #c4b5fd;
 
   --danger: #f87171;
@@ -191,6 +197,9 @@
   --chart-4: #d97706;
   --chart-muted: var(--border-strong);
 
+  --bg-glow: radial-gradient(ellipse 80% 50% at 50% -10%, rgba(139, 92, 246, 0.12), transparent 60%);
+  --card-shadow: 0 1px 0 rgba(255, 255, 255, 0.05) inset, 0 8px 24px rgba(0, 0, 0, 0.35);
+
   color-scheme: dark;
 }
 
@@ -228,6 +237,8 @@ body {
 
 body {
   background: var(--bg);
+  background-image: var(--bg-glow, none);
+  background-attachment: fixed;
   color: var(--text);
   font-family: var(--font-sans);
   -webkit-font-smoothing: antialiased;
@@ -261,7 +272,7 @@ body {
   background: var(--surface);
   border: 1px solid var(--border);
   border-radius: var(--radius-md);
-  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
+  box-shadow: var(--card-shadow);
 }
 
 .btn {