feat: Redesign Dark Mode with balanced purple theme

- Change Dark Mode accent from blue to purple (#a855f7)
- Balance dark backgrounds to match Light Mode structure
  - bg-base: #1a1a1a (was #0f0f0f - too dark)
  - bg-surface: #212121 (more balanced)
  - Improved contrast and readability
- Update borders to be more visible (12% vs 8% opacity)
- Adjust agent colors for purple theme:
  - Orchestrator: Purple
  - Researcher: Green
  - Negotiator: Orange
  - AR Manager: Yellow
- Update Settings description: 'Violett' instead of 'Blau'
- Dark Mode now mirrors Light Mode balance (just inverted)

agents/budget_manager/personality.md

@@ -1,2 +0,0 @@
-Du bist trocken, steif und hörst auf den Namen Hans-Ruedi
-

static/style.css

@@ -3,29 +3,29 @@
 @import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=JetBrains+Mono:wght@400;500&display=swap');
 
 :root {
-  /* Dark Mode - Aufgehelltes Schwarz */
-  --bg-base:        #0f0f0f;
-  --bg-surface:     #1a1a1a;
-  --bg-elevated:    #242424;
-  --bg-hover:       #2e2e2e;
-  --bg-glass:       rgba(26,26,26,.8);
+  /* Dark Mode - Ausgewogene dunkle Grautöne (angelehnt an Light Mode) */
+  --bg-base:        #1a1a1a;
+  --bg-surface:     #212121;
+  --bg-elevated:    #2a2a2a;
+  --bg-hover:       #333333;
+  --bg-glass:       rgba(33,33,33,.85);
   
-  /* Accent - Electric Blue (Dark Mode) */
-  --accent:         #0a84ff;
-  --accent-light:   #409cff;
-  --accent-dim:     #0070e0;
-  --accent-glow:    rgba(10,132,255,.2);
+  /* Accent - Violett (Dark Mode) */
+  --accent:         #a855f7;
+  --accent-light:   #c084fc;
+  --accent-dim:     #9333ea;
+  --accent-glow:    rgba(168,85,247,.2);
   
-  /* Neutrals Only */
-  --text-primary:   #ffffff;
-  --text-secondary: #a0a0a0;
-  --text-muted:     #606060;
+  /* Text Colors - Ausgewogen wie Light Mode */
+  --text-primary:   #f5f5f5;
+  --text-secondary: #a3a3a3;
+  --text-muted:     #737373;
   
-  /* Minimal Borders - Almost Invisible */
-  --border:         rgba(255,255,255,.08);
-  --border-accent:  rgba(10,132,255,.3);
-  --shadow:         0 30px 60px rgba(0,0,0,.5);
-  --shadow-sm:      0 2px 20px rgba(0,0,0,.3);
+  /* Borders - Sichtbarer wie Light Mode */
+  --border:         rgba(255,255,255,.12);
+  --border-accent:  rgba(168,85,247,.3);
+  --shadow:         0 30px 60px rgba(0,0,0,.4);
+  --shadow-sm:      0 2px 20px rgba(0,0,0,.2);
   
   /* Code/Pre Text - Zartes helles Grau für Dark Mode */
   --code-text:      #d4d4d4;
@@ -664,11 +664,11 @@ hr { border-color: var(--border); opacity: 1; }
 /* ── Agent Color System - Minimal ─────────────────────────────────────────── */
 
 :root {
-  --agent-orchestrator: #0a84ff;
-  --agent-researcher:   #32d74b;
-  --agent-negotiator:   #ff453a;
-  --agent-ar_manager:   #ffd60a;
-  --agent-default:      #64d2ff;
+  --agent-orchestrator: #a855f7;
+  --agent-researcher:   #10b981;
+  --agent-negotiator:   #f97316;
+  --agent-ar_manager:   #eab308;
+  --agent-default:      #8b5cf6;
 }
 
 .agent-orchestrator { color: var(--agent-orchestrator) !important; }

templates/settings.html

@@ -27,11 +27,11 @@
           <div class="mb-4">
             <label class="form-label fw-semibold">Design-Theme</label>
             <select class="form-select" name="theme" required>
-              <option value="dark" {% if theme == 'dark' %}selected{% endif %}>Dark Mode (Blau)</option>
+              <option value="dark" {% if theme == 'dark' %}selected{% endif %}>Dark Mode (Violett)</option>
               <option value="light" {% if theme == 'light' %}selected{% endif %}>Light Mode (Rot)</option>
             </select>
             <div class="form-text">
-              <strong>Dark Mode:</strong> Dunkler Hintergrund mit blauen Akzenten<br>
+              <strong>Dark Mode:</strong> Ausgewogene dunkle Grautöne mit violetten Akzenten<br>
               <strong>Light Mode:</strong> Heller Hintergrund mit roten Akzenten
             </div>
           </div>